How do the blind tell the difference between different paper money, and do any countries use braille?

In the US all bills are exactly alike as far as thickness, size, etc. New bills are being printed that have large numbers and high contrast for those with some usable vision, but there is no way to tell the bills apart by touch.

In the UK and Australia, different notes are different widths and lengths but it's something you have to learn, or you can use a gadget called a note gauge to measure them.

In Canada they are rolling-out a new paper currency that embosses a select number of Braille cells for each denomination.

I saw in the movie Ray that Ray Charles would insist on being paid in one dollar bills so that his employer couldn't pull one over on him. What it comes down to is in the US you would need someone else's assistance to determine the different bills and then develop a method of keeping them.

It is difficult for visually impaired people to tell the difference between notes of any denomination other than dollars by touch. Hence the saying "no cents, no feeling."

China have put braille on their Yuan notes for quite a long time. The latest roll off of Maltese notes (the ones with Mellieha) do have braille, but it an odd place, so the blind probably couldn't find the braille either. Notes in both of these countries are fairly obvious to find out by size anyway, but China was one of the first ones to put braille on their notes.

It surprises me that the Euro notes don't have braille on them. I'm pretty sure some Icelandic notes have braille on - the highest denomination (the 5000) definitely has some form of raised dot patterns on it.

Technology and scanners have made it easier for them to tell apart bills that are the same size. (Canada and the US are the only major countries with bills of the same size.)

Numerous countries use braille or raised markings to help blind people distinguish notes. Bright colors help those who can see but not too well.

http://time.com/money/4073753/blind-people-tell-money-bills-apart/#.
http://www.davidairey.com/banknotes-for-the-visually-impaired/