Did you know that at Superstore you could get your item free (up to $10) if it doesn't scan the right at the till?!
The other night, I happened to be waiting in line when a customer complained about an item being scanned wrong and that she should get it free. Unfortunately, it only took up 10+ mins to get it resolved. They were really annoyed by that time as was I but I learnt something new so the experience wasn't all wasted.
Next time, you're at the till, check the scan policy. It'll look similar to the photo above. After googling this , it seems this is a general practice by other retailers. You can read more http://canadianbudgetbinder.com.