In an effort to speed up Point of Sale transactions, the sales from the POS session do not affect the stock and accounting ledgers until a Closing POS Voucher is submitted for that session:
Each transaction from the POS screen now creates an intermediate invoice (called a POS Invoice) which doesn’t update the stock and accounting ledgers to keep it as fast as possible. This is also called a “sub-ledger”. Separating the POS ledger from the General Ledger makes the system a lot more scalable.
The stock and accounting entries are now created at end of day while closing a POS session with a single sales invoice which merges all the intermediate invoices created throughout the day.
This single consolidated sales invoice only creates 3-4 ledger entries.
Since drastically fewer ledger entries are made, the load on the general ledger is also eased, making it faster.
While it is true that the Stock Ledger will not include transactions from any active POS session, the stock levels from this "sub-ledger" will update the Stock Projected Quantity Report so the POS will not over estimate existing inventory in the store / warehouse.
Stock > Stock Reports > Stock Projected Quantity
In the above image, the "Actual Qty" column represents the value of the stock ledger. The "Reserved for POS Transactions" represents the "Actual Qty" less what quantities are currently reserved because of active POS sessions that have not yet made entries on the Stock Ledger.
Note also that "Projected Qty" ("Active Qty" less quantities reserved for the POS, production, etc.) adds a quantity of 100 to the first line item because of an order for 100 units that has yet to be received.
Within the Point of Sale, however, quantities on order but not received will not be reflected in the "Available Qty at Warehouse" field in the Item Details view.
In the instance below, as there is not enough quantity on-hand, the transaction won't be permitted. This applies to all active POS sessions at the current time.