The commission may fix terms and conditions for the sale or other disposition of any authorized issue of bonds. The commission may sell bonds at less than their par or face value, but no issue of bonds may be sold at an aggregate price below the par or face value thereof if such sale would result in a net interest cost to the commission, calculated upon the entire issue so sold, of more than 7 percent per annum, payable semiannually, according to standard tables of bond values. All bonds issued and sold for cash pursuant to this chapter shall be sold on sealed proposals to the highest bidder, either bidding alone or in conjunction with others, after advertising for bids by publication of notice of sale once, not less than 10 days prior to the date of sale, in a newspaper of general circulation printed and published in the City and County of San Francisco. The commission may reject any and all bids submitted and may thereafter sell the bonds so advertised for sale at private sale to any financially responsible bidder, either bidding alone or in conjunction with others, under such terms and conditions as it deems most advantageous to its own interest, but the bonds shall not be sold at a price below that of the highest bid which was rejected. The commission may contract loans and borrow money through the sale of bonds to the United States of America or any of its departments or agencies, upon such terms and conditions as may be agreed to. Such bonds shall be subject to all other provisions of this chapter, except the requirement that bonds be sold on sealed proposals to the highest bidder after advertising for bids.