"Do you think if you went back there at a later date, talked to the same cashier and the cashier would be able to give you the difference?"

Yes they would be able to give it to you. All you have to do is come back at the shift count. If the bank is over, they will run the tape, and pay you.

"I don't feel bad for someone getting fired for not doing their job well."

I would be ashamed to say that in a public forum.

"It's the downfall of American society"
One of the downfalls of American society is we have too many people that don't care what happens to other people.