When you do the good, you get the good in return, this money had to think about the owner of the money. What if it was a poor man, that had no except that money? He would have done the right thing, which is handle it to the cashier, weither it's his money or not, the cashier will take it or not; I will find it or not. That's something that doesn't concern him, the right thing was him giving the money, which is doing the right thing infront of God. But once he takes it and he knows someone in this place lost it he might return for it, that's not right; I mean God's watching him.
And there is something called lost and found in restaurants and markets and so.
And if the cahsier pocketed the cameras will show so, and he will be busted. So it's for his own good to say the truth.

"Better in time...down just like that"