In case any or all bids under section 129.18 of the Revised Code for the certificates are rejected, the proposals shall remain open for any further bids, and the board of commissioners of the sinking fund may enter into arrangements with any persons therefor, at a rate of premium or par, as provided in such section, not less than the highest and best bid. In case no bid can be procured, new proposals may be invited at such time as the board determines, but no portion of the certificates shall be sold or disposed of at a rate or price less than the amount expressed on the face thereof, nor shall any commissions, expenses, or charges be allowed on the sale or conversion thereof into money, which will reduce the net amount realized below the amount expressed on the face of the certificates so issued. No certificate shall be issued bearing a rate of interest exceeding four per cent per annum.