Avanza Supermarkets puts its groceries on sale, but then charges customers 10 percent extra when they get to the cash register, virtually wiping out some of the sale prices. It's a new pricing program that the company, Nash Finch based in Minneapolis, began in its stores in Colorado.

Most shoppers do not notice that the extra charge has been added to their bills until they look carefully at their receipts.

"I don't usually read the fine print, I just look to see what the sales are," said Antoinette Garcia of Denver. "I don't think that's fair. They should let somebody know before they do that."

When shoppers and 9Wants to Know asked store employees to explain the new pricing program, the store clerks and managers seemed confused.

"This is for taxes in Mexico and we think that people would feel better if they are charged for taxes as if they were in Mexico," one worker said.

"It's just a really weird, off-way to do business," said another clerk.

"Honestly, I don't know why they decided to lower the prices and then add the 10 percent," said an assistant manager in Denver.

"It's been a marketing tool, where we put a cheaper price out in front of the consumer," said a manager who would only identify himself as Jim. "We do it to cover freight and labor and to get the products to the shelf."

Nash Finch, which owns 50 grocery stores across the country, appears to only be tacking on the extra fee to its stores that cater to Hispanics.

The Nash Finch stores Avanza, Food Bonanza and Wholesale Food Outlets add the 10 percent charge to food at the register and specialize in serving Hispanics, according to store workers.

However, the Nash Finch stores Sun Mart Foods, Econo Foods, Family Fresh Market, Pick N Save and Prairie Market stores do not charge extra at the register and do not cater to Hispanics, according to the store workers.

"It's an injustice. They're targeting the people who can least afford it," said Susana Herrera after learning Nash Finch only charges the fee in stores that have specialty Hispanic foods.

"I feel if this were happening in King Soopers, at Target, at Walmart, there would be an outrage. People wouldn't put up with it," said Herrera. "But because the Spanish-speaking community mainly feel that they don't have a voice, they're afraid to make noise and they don't say anything. And I think they know that."

In a statement to 9NEWS, Nash Finch denied that it's targeting Hispanic shoppers with the 10-percent fee.

"The 'shelf-plus' pricing program is only used in certain store formats. These stores tend to be located where consumers are more price-conscious, as compared to our more conventional supermarkets," said Brian Numainville, Public Relations for Nash Finch Company. "The pricing policy is explained, not just in English, but also in Spanish, so that no customer is caught unaware at the cash register."

The stores do advertise that they are going to add a 10 percent fee in signs posted across the store, on the store shelves below the price of a food item on the store shelf and in flyers and circulars. However, the wording is confusing to many. For example, the flyers read, "A great way to save - Plus 10 % at the Register."

University of Denver Business Ethics and Law professor Corey Ciocchetti says he's never seen this kind of pricing before and questions if it's ethical.

"Businesses have a duty to not intentionally mislead their customers," said Ciocchetti. "The reason people come in here is because they can see, 'OK, this steak is $2.48.' Well, really it's not. It's 20 cents extra. But we don't see that going in."

Ciocchetti says while the stores are disclosing the fee in its flyers and store signs, it's written in fine-print and the wording can be confusing.

"It says plus 10 percent at the register. Is that a 10 percent discount? Is that a 10 percent tack-on, is it a tax, which would be problematic? It's just not clear," said Ciocchetti.

The Colorado Department of Agriculture's Office of Measurement Standards is investigating the pricing practice to see if it's legal.

"The business operator can charge whatever price that they want. But it's how its presented to and conveyed to the consumer that could mislead them into thinking they are getting a better value," said Nicholas Brechun of the Colorado Department of Agriculture. "Does it mislead the consumer into thinking they are getting a better value than what they're getting and can they price shop at a competitor? That's where the department is concerned."

Nash Finch could just raise its prices by 10 percent but stands by its policy of tacking on the extra fee at the register.

"Given the need to attract and retain customers, our stores cannot afford to alienate its customers by charging unexplained fees or unanticipated mark-ups. Our pricing is attracting customers, rather than losing them, demonstrating that the pricing policy is in fact fair, obvious and well-understood by shoppers," said Numainville of Nash Finch.

Nash Finch Company is the second-largest publicly traded wholesale food distributor in the United States with annual sales of $4.5 billion, according to the company Web site. It began the 10 percent pricing practice several years ago in its Wholesale Food Outlets and Food Bonanza stores and recently incorporated it in its Avanza supermarkets.

Read nine answers from the Nash Finch Company to specific questions posed in this 9Wants to Know investigation.

If you have a story tip, please e-mail Deborah.Sherman@9NEWS.com