What bothers me the most about this is that the OP paid with exact change. This means he/she should not have been expecting ANY money in return. This is not a case of "Oops! I got home and there's too much money in my wallet!" The OP knew the mistake was being made as it was being made and chose to accept the money anyway, knowing full well he/she was not entitled to it.
And, yes, if I was on a mystery shop, paying with exact change, and the clerk tried to hand me change back in error I would refuse it even at the risk of becoming "memorable." Better to be memorable than deceitful.
Edited 1 time(s). Last edit at 01/28/2016 05:20PM by meghan9262.