I have a 5 dollar bill in my pocket

About 30 years ago I went to see Steve Martin live when he was still just a stand-up comedian. The ticket cost 5 dollars at that time. During the show he joked about having 5 dollars and deciding what to do with them. He said something along the lines of, "You could have thrown them in the street but instead lined up to see me playing the banjo and telling bad jokes." I can't remember the punch line, but today I was thinking, this 5 dollar bill, what is it worth? Should I throw it in the street or should I run out and buy 4.5 Citi shares? Neither, a better investment would be a gallon of milk (I can still buy one for under 5 bucks if it's not organic) for my children. At least with them I am ensured of some sort of return.