I understand that you want to have a promotion where you are waving the tax on all sales for that one day.
Best way of doing this?
ANSWER
On the day of the sale, the easiest solution is to go to Utilities: Tax Rates.
In the ALL TAX RATES box, edit the tax rate and set the rate to 0.00.
All invoices for the day will be tax free.
When the sale is over, be sure to edit the tax rate and reset to the correct rate.
