Are you sure that the $5 is not being included on line 4b of Form 1040? Because of the stepwise nature of the tax tables, a $5 increase in your taxable income only has about a 10% chance of increasing your tax liability.
(I assume that you meant to say that you had no money in traditional IRAs on December 31, 2019, otherwise I would expect more of your Roth conversion to be taxable on your 2019 tax return.)
