Hi.
This should do it:
Turn key to PGM mode.
Type your new tax rate with 3 decimal places eg for 15 percent, type 15.000
Type 001 (if you only use 1 tax rate. if you have more, let me know)
Press TAX SHIFT
Press CASH/TEND
That should do it. Now turn back to REG mode and see if it works.
Mark, November 2008