The Department of Administration shall determine the amount of the petty cash accounts needed by each state agency and inspect the petty cash accounts at least once each year to determine that the total plus amounts of receipts for unreplenished disbursements is equal to the fixed sum of cash set aside. Shortages in petty cash accounts are a personal liability of the responsible head of the agency to whom the account is set aside. The department shall adopt necessary regulations governing use and replenishment of petty cash funds.