I think you know the answer to this already....take the $10 and buy a six pack of Pepsi .
Seriously - The fact that you are asking the question means that you know the right thing to do .Let the guy know that there is $10 extra dollars in there and ask that he return it to the manager and the next time you see the manager ask him if he got back the extra $10 that was left in the bag....As you know you can never trust those coaches
