If someone robs a bank then they can expect to serve at least 20 years in prison. That's the minimum. Of course if they did harm during the bank robbery then they can get even more time.
I read somewhere a few years ago where someone robbed a bank and injured one of the bank tellers and got 50 years in prison for it.
Injuring the teller by shooting at them added to the time he had to serve. Certainly not worth it.