Hi Gabby. If it beeps on and off constantly then it means there is a printer fault. Check for any paper jams and remove the ink roller from the printer. Leave the key in REG position and turn off/on at wall. Press Clear (CL). If it starts beeping again, the printer will need repair. It happens most commonly if the machine is around cooking areas where the grease builds up in the printer.
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If anyone needs more information, the Sharp XE-A102 manual is here:
http://the-checkout-tech.com/manuals/cashregisters/Sharp_XE-A102_operating_and_programming_manual.html
Registerman, December 2011