Hello, AnnAtTaxes,
I think what you are saying is that the 1099 is itself a tax document, and TT should not round entries on the 1099. When this happens, you may be able to overwrite the entries, but if you do so, TT may then not allow you to file online because you have overwritten "calculated" fields which should have been imported as written instead of calculated. I have actually gotten a letter back from the IRS in a past year because of this problem.
However, if it is from other tax software, it is okay for entries to be rounded to the nearest dollar. It is only the official forms that should not be rounded. Mainly it's not a problem--where I ran into trouble was with 12 monthly entries that were rounded first, then summed, rather than being summed first, then rounded. In most cases the result is both insignificant and not a problem.
All the same, if it is a problem, go back to paragraph 1 :-).
