Mistake #3: Leaving the receipts behind.
This is one of the worst mistakes you could ever make. You should always take the receipt and you MUST skim it before leaving the grocery store. Why? Well, the most reasonable answer to that are incorrect charges to your account. Do you want to pay twice for your chicken breast? Is it ok for you to pay full for a sale item? If you are ok with that, then, by all means don’t bother.
But it’s not right. If you see an error, that’s because you checked the invoice before starting your car, then go straight to the customer service counter. Yes, that would be YOU. And it can save you big bucks.