N.Y. GBS. LAW § 518 : NY Code - Section 518: Credit card surcharge prohibited

No  seller in any sales
  transaction may impose a surcharge on a  holder  who  elects  to  use  a
  credit card in lieu of payment by cash, check, or similar means.
    Any seller who violates the provisions of this section shall be guilty
  of a misdemeanor punishable by a fine not to exceed five hundred dollars
  or a term of imprisonment up to one year, or both.