Vendor bill tax amount override doesn’t save for small corrections (snaps back to calculated value), causing QBO mismatches

Problem
A user edits the Tax amount on a vendor bill to match the vendor’s invoice and clicks Save. The value reverts to the previous tax amount. This happens on every attempt. Large edits seem to stick, but 1–5 cent corrections never do.

Likely root cause
The override is saved as a rate, not as a dollar amount. That rate is rounded to 3 decimals and the tax is then recalculated from it.

• Inv 1161: 236.89 ÷ 4,965.64 = 4.7706%, which rounds to 4.771%. 4.771% × 4,965.64 = 236.91.

• Inv 1164: 542.28 ÷ 10,845.00 = 5.0003%, which rounds to 5.000%. 5.000% × 10,845.00 = 542.25.

One rate step (0.001%) is worth about $0.05 to $0.11 on these bases, so cent-level corrections can’t be stored.

Expected behaviour

• A manual Tax amount override is stored as the exact dollar value entered.

• That exact value syncs to QBO.

• The rate shown is for display only and is not used to recalculate a manual override.