§ 6313.
In the payment of any tax imposed by this title, 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 1 cent.
([Aug. 16, 1954, ch. 736], [68A Stat. 778]; [Pub. L. 94–455, title XIX, § 1906(a)(19)], Oct. 4, 1976, [90 Stat. 1825].)