N.J. Stat. § 54:39A-9
Every user shall keep records, in such form as the director reasonably may prescribe, as will enable the user to report and enable the director to determine the total number of over-the-road miles traveled by the user's entire fleet of qualified motor vehicles, the total number of over-the-road miles traveled in New Jersey by said entire fleet, the total number of gallons of motor fuel used by said entire fleet, the total number of gallons of motor fuel purchased in New Jersey for said entire fleet, and such additional information as the director may prescribe as is required to determine the taxes payable or collectable under this act. All such records shall be safely preserved for a period of four years in such manner as to ensure their security and availability for inspection by the director or any authorized assistant engaged in the administration of this act. Upon application in writing, stating the reasons therefor, the director may, in the director's discretion, consent to the destruction of any such records at any time within said period. The director or the director's authorized agents and representatives may, at any reasonable time, inspect the books and records of any user subject to the tax imposed by this act. The director shall provide by regulation for any such examination of books and records to be conducted at the office or offices of the user where such books and records are maintained.
N.J.S. § 54:39A-9