If you use a Casio MS-80TE to calculate taxes, it is of course important to know how to change the rate at which they are calculated, in the event of a tax rate change or a move to a place with a different rate.
Setting the Tax Rate
Hold down the "Set %" button until "SET 0" appears in the display.
Press the "TAX+" button. The display should now show "TAX SET %" and the current tax rate.
Input the new tax percentage.
Press "SET %".