FYI, I received precisely the same response/explanation as @Scotca did, and I discussed it with the CPA who wrote it. To be clear, there is no "fix" coming, so don't wait for one. They made the switch to transaction-level rounding intentionally and do not view it as a bug, so they will not be updating their software to "fix" it. The guy I spoke with left open the possibility that they'll revisit the issue for next year based on the feedback they're receiving, but he made even that sound pretty unlikely. He said they made the change to be more consistent with IRS instructions about rounding and to be more in line with the "industry standard" approach.
Although this obviously wasn't the answer we were hoping for, I do feel satisfied that we now have the official, decisive response from Intuit on this question, so we can now all go about finishing our taxes. I am satisfied that any discrepancy between our 1099-B and TT's calculated capital gain will be acceptable to the IRS and will not trigger an audit. So really it's up to each of us whether you want to file with the discrepancy or use the workaround of reporting summary transactions and then mailing your 1099-B to the IRS w/form 8453. Personally, I will be using the workaround because all the rounding results in a capital gain calculation that is significantly higher than my actual capital gain. If the discrepancy were in my favor, I'd probably just go along with it.
