A maximum of 20 percent of the bonds authorized by each Bond and Capital Improvements Act of the State may be sold by the State directly to retail purchasers or to financial intermediaries, or to an underwriter who agrees to use its best efforts to sell such bonds to retail purchasers or to any intermediaries, such bonds to be herein referred to as “retail bonds.” The Secretary of Finance, the State Treasurer, the Director of the Office of Management and Budget and the Controller General are hereby authorized to determine the terms and conditions of the retail bonds, and the manner, whether at public or private negotiated sale, by which they shall be awarded to the purchasers thereof, notwithstanding anything to the contrary contained in this chapter; provided, that the requirements of § 7422 of this title must be observed.