Only Congress is allowed to make that decision, so trump's demand is unconstitutional. The US Government makes so much by producing twenty dollar bills, that the cost of making a cent is a rounding error. But by questioning the money, trump is causing inflation, which means we will lose more money than we gain. Random addition, for every two pennies you remove, you need to produce an extra nickel. The penny costs about 3.2 cents to produce, so you save 4.4 cents, but the nickel costs 13.8 cents to produce, so you lose 8.8 cents, for a net loss of 4.4 cents in just production costs.