On the first business day of January and the first business day of July of each year a computation shall be made to determine whether the mileage reimbursement allowed in section 1 of P.L.1943, c. 188 (C. 52:14-17.1) is to be adjusted on that date according to the following formula:
C.P.-B.P.
Adjustment = ...........
18
where:
a. Adjustment means the result of the above calculation in the number of whole cents plus one-half cent where the remainder is five-ninths or greater;
b. C.P. means the price paid for regular gasoline by the State on the date of the computation; and
c. B.P. means the price paid for regular gasoline by the State on the effective date of this amendatory and supplementary act.