"Not sure what you mean by "the software typically starts the rounding early in the computations." "

Take a look at that instruction:

Line 1: Total qualified net income from all qualified taxpayers (combine all box a amounts from the Schedule of Qualified Taxpayers below, Side 2, and any additional pages).

Also, each partner section has their own line b:

b. Elective tax credit amount (Multiply box a by 9.3% and enter the result.).

That's exactly the issue I brought up, and why the State won't bother with a couple of dollars of rounding drift. We don't know this programming, but I know programming and I know drift. Let's review why they have set up the discrepancy with this form.

You enter each taxpayer's amount at the Scheduled details, and the 9.3% is applied there. See what sort of non-whole dollars you get. See what each has for the least significant decimal you get.

Then add up the "raw" data from that Schedule (each partner). Go out to as many decimals as you want to consider.

Then, do the math for the top section as you stated: total income and multiply by the 9.3% here.

This is why your own calculations and the software will differ. It's called Drift, not Error, because Drift is the accumulative difference. It's not an error. It's Mathing just fine. Let me offer an example:

If you have 6 people at, for an example, $222 each, that total = $1332, * 9.3% = $123.876, which rounds up to $124. This is your Top Section. That's the Partnership perspective.

Also, though, on this form, for each partner in the second section: $222 * 9.3% each = $20.646, which rounds up $21, and then $21 * 6 = $126. That's the math when you carry the already-rounded amount to the top section.This is the Partner perspective.

$2 Drift.