N.J. Stat. § 40:37-223
At the sale, the real estate shall be publicly sold to the person who will take the same for the shortest period of time, not exceeding fifty years from the date of sale, and pay to the commission before the close of the sale the full amount due upon the unpaid assessments, with interest thereon from the time when the same was confirmed at the rate of six per cent per annum, together with such sum as the commission may fix and determine to be a fair proportion of the expenses of advertising, conducting and making the sale.
If any purchaser fails to make such payment, he shall forfeit all claim to the real estate, and the same shall be resold by the commission after advertisement in the manner provided in section 40:37-222 of this title.
N.J.S. § 40:37-223