Just had a quick question I work in Retail and work the register at a shoe store. Tonight I found an extra hundred dollars that I didn't add to my deposit. Can I just tell my boss that I was $100 bucks over and get fired, or just tell my boss I found 2 $50 Bills just laying around? In a Pickle, Thanks

How about just telling the truth?

I have a feeling that you kept 100 because you added wrong and thought it was overage that was free money, and then added again and realized you were wrong?
Whatever you say is going to be suspect.
If I'm wrong, please explain exactly what happened, and maybe we can help.

You tell the truth, if you tried to steal the 100 dollars, most likely you will get fired.
If your drawer is 100 dollars short, most likely you will get fired.

But, the truth is always best.

On top of that most places have cameras focused on the tills and where the tills will be counted. This is a security measure to prevent cashiers from doing dodgy things. So... Talk to your manager. It is better to deal with this with integrity then see how it comes out of the wash.

To remember in the future, regardless of what happens:
1). If the float doesn't line up with what you should have, count again.
2). If anything goes sideways, Severely over or under, go to your manager. The worst that will happen I that you'll get written up.

The question of whether you will be fired or not has not been answered, nor can it be. When I worked as a cashier at a new store, we were hit with a quick change artist. If you aren't familiar with what they are, they fast talk you into breaking larger bills for them. I was one of those hit and my register was short that day. I was not fired because the bosses understood I was new to cashiering so it was more a problem of their training.

But we can't tell you what your boss will do.