Just to prevent anyone else wasting their time trying this--the rounding was causing my total gains to show around $200 less than reported on my 1099-B imported directly from the TDA website.
So I decided to see what would happen if instead I manually exported from TDA to a .txf file then imported that file.
For some reason that came up with a new *third* number for the total gains that disagreed with both the 1099-B and with TT's previous total--this time around $300 less than my 1099-B. Worse, it didn't know which transactions were Box A, Box B, etc., so wanted me to manually enter that for every single trade.
So--yeah, don't waste your time trying that.
