"..Trump said he's doing this because it costs too much, but the actual law is
31 U.S. Code § 5111 - Minting and issuing coins, medals, and numismatic items
The Secretary of the Treasury— (1)shall mint and issue coins described in section 5112 of this title in amounts the Secretary decides are necessary to meet the needs of the United States;.."
"...Trump Tells Treasury Secretary to Stop Minting New Pennies..."