The key thing is you should not bill on multiple systems for a single register in SlickPOS.
Click on setup on left bottom of the screen.
Select "preferences". Now enable sequential local receipt numbers.
Once you go to sell now it will give you a warning, to not be logged in multiple systems to bill.
if you switch systems, make sure the last receipt number is correct. Before you start billing in a new system.
Published on: 16 / 02 / 2018