26 U.S. Code § 6102 - Computations on returns or other documents
(a) Amounts shown on internal revenue forms
The Secretary is authorized to provide with respect to any amount required to be shown on a form prescribed for any internal revenue return, statement, or other document, that if such amount of such item is other than a whole-dollar amount, either—
(b) Election not to use whole dollar amounts
Any person making a return, statement, or other document shall be allowed, under regulations prescribed by the Secretary, to make such return, statement, or other document without regard to subsection (a).