When I worked at Wallyworld, I got suspended for a day because of giving $10.00 back too much. I had close the cash register and count to make sure. Was put on probation for a week after I came back. Come to find out the person I gave too much to brought back the extra. I had a stack of brand new bills and one stuck to the other. They also did another background check to make sure they didn't overlook anything. So I not only lost 8 hours pay and of course had to repay the $10.00 and never got reimbursed after the money was brought back. So absolutely give the money back. They also make note in the employee file that the employees cash draw came short on occasion. That makes it sound like it happened a lot. I would try to return it ASAP before the employees shift was over. I couldn't live with myself. it isn't the recipient's money.