N.J. Stat. Ann. § 46:30B-17

Limitation on holder's power to impose charges. A holder may not deduct from the amount of any instrument subject to R.S.46:30B-16 any charge imposed by reason of the failure to present the instrument for payment unless there is a valid and enforceable written contract between the holder and the owner of the instrument pursuant to which the holder may impose a charge, and the holder regularly imposes the charges and does not regularly reverse or otherwise cancel them. The amount of the deduction shall be limited to an amount that is not unconscionable.