31 U.S.C. § 5101

Decimal system

United States money is expressed in dollars, dimes or tenths, cents or hundreths, 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 .)