Yes they are treated differently based on box category. When the bug was initially introduced in 2020, all trades started rounding trade by trade. But this made Box A and D trades sum to a different result compared to the forms sent to the IRS from the brokerages. Last year they fixed the bug for Box A and D, but left the loophole open for B, C E and F so you can still use it for crypto.
I spent way too much time speaking with the office of the president last year about this bug, because this forum is full of misinformation. They are adament that it is a feature, not a bug. And recommended that those that know about it should submit 1099-B with 0 taxes owed in the worst case, or a tax refund (maximize favorable rounding for both losses and gains) in the best case.
They make this suggestion to avoid admitting that they've violated their 100% accuracy guarantee. Instead catering to the big clients looking for tax loopholes.
Again, I spent way too much time speaking with office of the president about this last year. They are very careful with their use of words, avoiding things like bug or loophole or evasion, but did confirm that a single trade with gains of $99 would result in gains tax when using Box B C E or F, but the same trade entered in the worksheet as 200 individual trades with gains of $0.495 would have no gains tax. For Box A and D, both those scenarios would result in the same gains tax.
