On or before the fifth workday after the end of each month, the comptroller shall determine as accurately as possible for the period since the latest determination under this section the number of gallons of undyed diesel fuel used for purposes other than to propel a motor vehicle on the public highways of this state. From the number of gallons so determined, the comptroller shall compute the amount of taxes that were paid on that undyed diesel fuel and shall allocate and deposit that amount to the credit of the general revenue fund.