How do blind people know what bill is in their hand? Should there be Braille on U.S. currency?

I was watching Slumdog Millionaire when the poor kid that sings and was blind is able to recognize a U.S. bill by smelling it, but only because a young Jamal told him that the monetary value was a $100 he then knew the amount he received. Anyways, blind people really have to trust what the cashier or person closest to them is saying about what the value of their money is or nonetheless, giving them back the correct amount of change. Back to my question, is there a way in the U.S. or any other country that has some type of system for blind people to know what the number on their money is or is there a system in place that I am completely unaware of?