27 CFR § 70.62
Fractional parts of a cent
April 24, 2020
In the payment of any tax, a fractional part of a cent shall be disregarded unless it amounts to one-half cent or more, in which case it shall be increased to one cent. Fractional parts of a cent shall not be disregarded in the computation of taxes.
[T.D. ATF-251, 52 FR 19314, May 22, 1987. Redesignated by T.D. ATF-301, 55 FR 47606, Nov. 14, 1990]