New York Subway Card Refill Caculator.
Use this calculator to minimize the leftover amount when purchasing additional rides on a stored-value MetroCard. Given the current balance, a table with all possible rides will be shown. The leftover amount is usually no more than a nickel. Rates used were valid as of June 2015.
This app is most likely to be useful to tourists or other occasional users of the New York MTA Subway system.
Application does not require any special permissions and works offline.