The board of county commissioners of any county having a population of more than one hundred fifty thousand (150,000) may by resolution adopted by such board, authorize the establishment and maintenance of a petty cash fund in any county office in an amount not to exceed two hundred dollars ($200) at any one time. The board shall provide written instructions specifying the purposes and conditions for which the petty cash fund can be used. When the fund is authorized hereunder a county warrant shall be issued to establish the petty cash fund.