"Is it worth returning the money to the seller if he was wrong?" - Market case

This happens to me regularly, not every day, of course, but I stopped being surprised at this. Yesterday I went to the market for meat, there is a point where they sell cheaper.

On the market

I walk in, and there is a new saleswoman, I begin to discuss with her which piece to choose, she has a funny insert in the sentences - "Okay". A cutter emerges from the back room, and begins to explain for pricesclaiming that they are at the level of wholesale. And he speaks as if I am indignant, jokingly told him about this, was embarrassed and dived back to his place.

Sellers are wrong too

In general, I chose two pieces, they pulled at 1176 rubles, I give 1200 rubles, the new girl is counting the change. After the first 500 rubles bill, I understand that they are overpaying me again, and my grandma is standing next to me and is indignant at the slow service. My change reaches 700 rubles. with a penny! I ask the saleswoman to recount, pointing out the error, she changes in face and counts 24 rubles.

Grandma praised?

The butcher comes up again, I smile, I say, I didn’t buy a little below the wholesale price! And grandma comments sarcastically: “They will put you a plus sign in the next world». I want to joke in response about the quality of the meat, that it is unlikely to lead to a plus sign, but the situation is heating up, my jokes are not successful. And as a person who has done a good deed, I hurriedly retreat, and only after I hear from the newcomer - an honest buyer.

Such is the story, but how do you act in this case?