26 U.S.C. § 7504 - Fractional Parts of a Dollar

The Secretary may by regulations provide that in the allowance of any amount as a credit or refund, or in the collection of any amount as a deficiency or underpayment, of any tax imposed by this title, a fractional part of a dollar shall be disregarded, unless it amounts to 50 cents or more, in which case it shall be increased to 1 dollar. (Aug. 16, 1954, ch. 736, 68A Stat. 896; Pub. L. 94–455, title XIX, § 1906(b)(13)(A), Oct. 4, 1976, 90 Stat. 1834.)