When deemed necessary by the purchasing agent, bid deposits shall be prescribed in the public notices inviting bids. Upon entering into a contract, bidders shall be entitled to return of bid deposit where the purchasing agent has required such. A successful bidder shall forfeit any bid deposit required by the purchasing agent upon failure on his part to enter into a contract within fourteen (14) days after the award; provided, however, that the city, in its uncontrolled discretion, may waive this forfeiture.