N.J. Stat. § 40A:11-21
A person bidding on a contract for the erection, alteration or repair of a public building, structure, facility or other improvement to real property, the total price of which exceeds $100,000, shall furnish a guarantee as provided for herein. A contracting unit may provide that a person bidding on any other contract, advertised in accordance with law, shall furnish a guarantee as provided for herein. The guarantee shall be payable to the contracting unit so that if the contract is awarded to the bidder, the bidder will enter into a contract therefor and will furnish any performance bond or other security required as a guarantee or indemnification. The guarantee shall be in the amount of 10% of the bid, but not in excess of $20,000.00, except as otherwise provided herein, and may be given, at the option of the bidder, by certified check, cashier's check or bid bond. In the event that any law or regulation of the United States imposes any condition upon the awarding of a monetary grant to any contracting unit, which condition requires the depositing of a guarantee in an amount other than 10% of the bid or in excess of $20,000.00 the provisions of this section shall not apply and the requirements of the law or regulation of the United States shall govern.
N.J.S. § 40A:11-21