It had better be old. The subway a nickel? I've also seen it on the web as "three nickels."
Unfortunately, I haven't seen it recorded that early.
9 December 1980, Christian Science Monitor, pg. B16:
An old New York Yiddish maxim holds that: "Three nickels will get you on the subway, but garlic will get you a seat."
1 July 1981, Wall Street Journal, pg. 1:
In New York in the days of the five-cent subway, they used to say that you could ride the subway for a nickel but garlic got you a seat.