An Iqaluit man is warning shoppers to check their grocery store bills, after discovering shelf prices didn't always match scanned prices at checkout.

Thomas Ahlfors, who shops at Iqaluit's NorthMart, said that three times in one week, the price on the shelf did not match the scanned price at the checkout counter.

"I figured enough is enough," he said. "I went on the internet and found the full policy and the North West Company's name was right on there with it."

What he found was a widely known but often forgotten rule of Canadian retail: Whenever there is a discrepancy between an item's shelf price and the price scanned at the register, customers are entitled to get $10 off. If the item is less than $10, it’s free.

The rule is enforced at many Canadian retailers who abide by a voluntary scanner accuracy code, including the main northern grocers: the North West Company, Arctic Cooperatives and Loblaws.

"If your company has committed to supporting the code, that commitment comes as one we trust the company to take seriously,” said David Wilkes, vice-president of the Retail Council of Canada's grocery division.

The code also states stores should clearly post the price of items on store shelves next to the product, and should take steps to fix discrepancies between scanned and posted prices as quickly as possible once errors are brought to their attention.

Wilkes said if the store refuses to honour the policy, consumers can lodge a formal complaint with the council.

Ahlfors, for one, said he will be a lot more vigilant at the checkout.

"It makes me a lot more careful as far as looking at prices," he said. "Obviously if you do a lot of shopping with a big cart full of stuff, I'm not going to remember all the prices. It's usually when it's the small stuff and the sales prices."