Dominic is right that abolishing the penny is a good idea. But if President Trump is going to stop production of the penny, he should ban the nickel, too.

As penny opponents have noted, it now costs 3.69 cents to produce a single penny, which has barely any value. But the problem with banning the penny in isolation is that it would increase demand for nickels, which cost 13.78 cents to produce, according to the U.S. Mint’s annual report. Therefore, the gap between cost of production and face value is even greater. This is the 19th consecutive year that both pennies and nickels have cost more to produce than their face value.

In contrast, the smaller dime only costs 5.76 cents to produce. So a shift from pennies and nickels to dimes would be much more cost effective.

Because so many pennies and nickels are manufactured, they are certainly some fixed costs that are absorbed by the production of those coins that would shift, and thus increase the per unit costs of other coins. But there is clearly more room to spare for dimes and larger value coins.

One argument against getting rid of lower denomination coins is that it could be inflationary, with businesses potentially rounding everything up. But at least when it comes to pennies, research has found that there wouldn’t be such an effect. Wake Forest University economist Robert Whaples studied sales tax and price data from convenience stores and found that sometimes prices get rounded down and sometimes they get rounded up. “The bottom line, as I see it, it basically isn’t going to have any impact,” he told Dow Jones Newswires.

Though that research concerned the penny, it’s hard for me to think that the nickel would prove any different.

When Trump was asked whether the nickel would be next, he laughed, and didn’t give a firm answer one way or another. But as long as he’s getting rid of useless and costly coins, he should scrap the nickel as well.