how do i reset sharp ER-A320 to factory defaults?

i got a used Sharp Er-A320 and i was trying to use it. i dont have any departments employees etc. i just sell used furniture, so example i sold a table for $50.00
so i hit 50.00 then #/TM/SBTL then CA/AT and it doesnt add the sales tax or display it. i cant figure out how to add sales tax and show it on the reciept and the display. all the reciept shows is 50.00 CA
the state sales tax here is 8.5% can you help me?

danny h.
October 2008