200
A matter of principle it became. The store overcharged by 250 for an item. They agreed after keeping you waiting for 15 minutes. They refunded. They didn't refund the tax, so with rounding, they only needed to refund 200. You thought it wouldn't make a difference, as the nearest coin is a 250.
They gave you two 100 coins. You didn't know they even existed.
You keep the two coins in your purse. The other day, on another visit, the bill came to something and 700. The check out person says "... and 750". You pay exactly by using those two 100 coins.
"We don't accept these", she says.
"But they came from this store, in my change."
She doesn't know what to say. You pick up the bags, and leave.
