Semi-Integrated is when the Payment Terminal is connected to the POS and can automatically get the transaction amount needed to close the sale.
To close a transaction use the "Debit/Credit Payment" function.
This will display a modal that will connect to the payment service; this talks with the payment terminal and sends the amount needed to close the transaction.
Once the customer completes the transaction on the Semi-Integrated terminal the transaction will close and a receipt will be printed (if enabled).