The county executive shall be authorized and empowered to employ, whenever he deems such employment for the best interests of the county, an agent or broker to assist in negotiating or selling any bonds, certificates of indebtedness or notes of the county and to pay for the services of such agent or broker out of the proceeds of sale or out of any other available funds of the county; provided, that the amount so paid in connection with the sale of the bonds shall not exceed one-half of one (0.5) percent of the face amount thereof, and in connection with the sale of certificates of indebtedness and notes, shall not exceed one-half of one (0.5) percent of the face amount thereof. (Mont. Co. Code 1965, § 2-109; 1933, ch. 158; 1969 L.M.C., ch. 40, § 2.)