Tab 1, change the Tax Schedule to something else, click Totals... then back to tab 1 and change the Tax Schedule back to the original value... check Totals again.

If you know how it happened, report to Sage.

Have you tried to recalculate the quote?

Changing tax worked, is that just a type of recalculation error in SAGE?  I assume I would have to know exactly what the user did to report to SAGE?

We don't know how it happens, but have seen incorrect SO totals in a few places.  Changing the tax schedule is just a way to trigger the Sage programming to recalculate the totals.

If you can reproduce the problem, please report the "how to" steps to Sage, so they can fix it.