Okay...   But the cash you used to pay the vendor is not part of Sales.   It is not a Sale or a Credit, so you don't need/want to see it entered in your "Sales" summary. 

Yes, it sounds like you used cash out of the POS drawer, but you could just as easily walked down to the ATM and taken out Cash to pay the vendor.   This was an Expense transaction.

I'm still missing why you can't reverse the Paid Out by showing a Paid In to make the Cash Drawer balance again.  But you still will need to enter the Expense separately.