Dear Wife prefers that I don't shop at the market. If something is too expensive, I won't buy it. If something rings up higher priced at the till, I'll complain to the clerk/manager and make them mark it down to the display price (always seems to happen just on their "special sale" items). Her approach to food is that if she wants something, she'll buy it regardless of the price. And if something rings up higher at the checkout, it's of no concern to her because she doesn't pay attention to the price anyways. That's just not me.
WalMart seems to be the worse offender in our town. They claim to have the lowest prices on the shelves, but you can't count on that at the checkout.

I'm so old that I remember a time when a store clerk would ring up your purchases, bag them for you, and even walk you out to your car and load the bags of groceries. Never needed that service when I was younger, but feel I lost out on something now that I'm at an age where little services like that would be appreciated.