§ 116. Certificates of deposit. The legislative body of a city may authorize and empower its chief fiscal officer, in his discretion, to issue certificates of deposit, each in the sum of ten dollars, or any multiple thereof, and at such a rate of interest, if any, as he shall prescribe and to sell the same for not less than their face value at private sale, in such manner and at such times as he deems best for the public interest so to do. The proceeds of such sales shall be used only for the purpose for which such certificates of deposit are issued. The certificates so sold as aforesaid may be used only by the holders thereof for the payment of taxes and/or assessments levied by the city when such taxes and/or assessments are or shall become due and payable, and such certificates shall be taken by the treasurer of such city for the payment of such taxes and/or assessments at the par value thereof and any accrued interest thereon, provided, however, that each such certificate shall cease to bear interest after the expiration of two years from the date thereof.