My recent findings:
I tried to see how HR Block and CreditKarma work with 1099-B forms and how they deal with this issue.
Both round each line and then calculate total amount. Therefore, It seems similar problem is everywhere and maybe it's even fine but I wouldn't like to deal with IRS and explain the difference in 1099-B and 8949.
Currently I see the only one way here:
Do not import 1099-B forms, choose Enter Manually, Select 4+ transactions. In this case Turbotax proposes to enter total amounts, broker names, EIN, etc. Amounts will be rounded but it's ok here since it's total only. And then Turbotax will ask to attach PDF file with the 1099-B form, which can be attached. And Then it can be e-filed, I hope. But It may not work for everyone. https://www.irs.gov/instructions/i8949
Exception 2.
Instead of reporting each of your transactions on a separate row of Part I or II, you can report them on an attached statement containing all the same information as Parts I and II and in a similar format (that is, description of property, dates of acquisition and disposition, proceeds, basis, adjustment and code(s), and gain or (loss)). Use as many attached statements as you need. Enter the combined totals from all your attached statements on Parts I and II with the appropriate box checked.
For example, report on Part I with box B checked all short-term gains and losses from transactions your broker reported to you on a statement showing basis wasn't reported to the IRS. Enter the name of the broker followed by the words "see attached statement" in column (a). Leave columns (b) and (c) blank. Enter "M" in column (f). If other codes also apply, enter all of them in column (f). Enter the totals that apply in columns (d), (e), (g), and (h). If you have statements from more than one broker, report the totals from each broker on a separate row.
Don't enter "Available upon request" and summary totals in lieu of reporting the details of each transaction on Part I or II or attached statements.
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Exception 2 is not available for the election to defer eligible gain by investing in a QOF. Taxpayers who elect to defer eligible gain must report the details of each investment in a QOF on Form 8949 in the manner described under How To Report an Election To Defer Tax on Eligible Gain Invested in a QOF, later.
