A bit more attention at the checkout—and planning in advance—will save you money.

While waiting in a line at Loblaws on Rideau Street last weekend, I overheard the guy in front of me inform the cashier that he was overcharged.

“These [biscuits] are on sale for three bucks,” he said, pointing to the $3.99 that was showing on the computer screen.

It’s the moment we all dread: “Price check,” which sounds a lot like Mayday, the distress call, when you’re tired and hungry.

I could feel my empty stomach start to grumble as some of the people standing behind me also let out a faint groan, shifting their weight from one leg to another as if we formed a giant caterpillar. A few customers turned to their mobile phones for a distraction from the pain. One clung to the magazine rack for support.

And as we braced for a longer wait that anticipated, something extraordinary happened. The package of eight sweets was given to the guy in front of me—for free!

It turned out that the biscuit buyer had been right and the manager, upon confirming that there was a discrepancy between the checkout price and what’s advertised in the store’s flyer, evoked something called the Scanner Price Voluntary Accuracy Code.

This code is kinda like the ring from Lord of the Rings—only its power rules all UPC barcodes at participating retail stores. Some retailers (click here to see the list) commit to accurate scanner pricing and with millions of items on shelves throughout the city, it’s not a matter of if—but when. When a price is wrong, each incorrectly priced item under $10 is to be given to the customer free of charge.

“I think every cashier knows about this.”

Few consumers know that these pricing errors can equate to more money in their pockets.

“I think every cashier knows about this,” says an employee at Market Organics, who explains that his store isn’t partnered with the code although savvy customers occasionally do ask.

Take note that while not every store honours the scanner price policy, most of the bigger companies like Costco, Loblaws, Metro, Sobeys, Walmart, Giant Tiger, Home Depot, and Canadian Tire are all on board.

Now once a mistake is found, how long does it take for the store to update its system? As I soon found out, it depends.

Curious, I went back inside the grocery store about 30 minutes later (after I had a meal) and picked up the same item that had caused such a stir.

“That’ll be $3.99,” said the cashier.

Sitting down with my own free box of snacks, I spoke with the manager on duty who explained that these mistakes do happen. She said that due to a communication error, the price hadn’t been updated in the store’s database and she now had two things to brief at the morning meeting: encourage cashiers to seek the attention of a manager sooner (especially then there are other customers waiting on a price check) and second; verify price corrections so that the system can be updated and future customers won’t be paying the wrong price.

Human-error isn’t going to perish like produce, suggesting that there’s likely no shortage of cash registers throughout the NCR where Ottawans will pay less if they pay more attention.

5 more grocery store tips

1. Price booklets

Akin to a food diary or journal, maintaining your own price booklet (hardcopy or digital) for the food you buy most often will help keep tabs on what’s a normal price and what a sweet deal. Click here for a free template or feel free to search online for plenty of other resources.

2. Per unit pricing

Look past the BIG sale stickers and focus your attention on the small print because most labels at the grocery store will display the Per Unit Price. This number can be very helpful for understanding what the item costs per set amount of weight—and acts as an excellent reference when comparing the cost of one product to another (including the same item when packaged in different quantities).

3. Apps

There are a number of mobile applications out there to help make grocery shopping easier such as Value Tracker (one-time cost of $0.99) as well free apps for the iPhone here and other devices here.

4. Online grocery price book

Some cities have a Grocery Price Book that helps keep track of the price for various items at different stores. It looks like Ottawa didn’t get much traction and even Reddit tried to resurrect the initiative. Maybe you’ll be the one who will pick up the torch.

5. Ottawa Public Health

A ten-year-old brochure from Ottawa Public Health has a few tips that prove to be timeless such as avoiding the grocery store on an empty stomach—allowing your brain to do the decision-making rather than your appetite.

Do you have tips for saving Apt613 readers’ money at the grocery store? Let us know in the comments below.