N.C. Gen. Stat. § 160A-269
A city may receive, solicit, or negotiate an offer to purchase property and advertise it for upset bids. When an offer is made and the council proposes to accept it, the council shall require the offeror to deposit five percent (5%) of his bid with the city clerk, and shall publish a notice of the offer. The notice shall contain a general description of the property, the amount and terms of the offer, and a notice that within 10 days any person may raise the bid by not less than ten percent (10%) of the first one thousand dollars ($1,000) and five percent (5%) of the remainder. When a bid is raised, the bidder shall deposit with the city clerk five percent (5%) of the increased bid, and the clerk shall readvertise the offer at the increased bid. This procedure shall be repeated until no further qualifying upset bids are received, at which time the council may accept the offer and sell the property to the highest bidder. The council may at any time reject any and all offers.
N.C. Gen. Stat. § 160A-269