31 U.S.C. § 5101Section
§ 5101. Decimal system
United States money is expressed in dollars, dimes or tenths, cents or hundreths,1 and mills or thousandths. A dime is a tenth of a dollar, a cent is a hundredth of a dollar, and a mill is a thousandth of a dollar.
(Pub. L. 97–258, Sept. 13, 1982, 96 Stat. 980.)