Enable the ability to have "No Receipt" and set that as the default.
  1. Go to Tickets > Sales Methods.
  2. Click Daily Sales.
  3. Go to the Itemized receipt options tab.
  4. Click "No Receipt" and click Mark Active.
  5. If you want the default to be to not print a receipt, go to the Delivery methods tab.
  6. Click on the default delivery method.
  7. Click Edit receipt default.
  8. Choose No receipt from the dropdown.
  9. Click Save.