Thank you. This was the answer. TTax in this case doesn't use the math to calculate the tax but relies on the simplified tax table. In this case (hypothetical), TTax would have made me pay $3 more than the IRS would require. This is disappointing to find out, but since it is hypothetical, I don't really care. Strange that they don't do the rather simple math to come up with a better answer for the filer.
