how to transfer data from POS to Quickbooks

We are using Quickbooks desktop but at the same time using POS RMS version-2. All sales transactions and inventory is recorded in POS while only bills are entered in Quickbooks. What is the appropriate method to transfer sales and inventory related transactions in Quickbooks from POS. Is this a practice in some other companies?

There are three methods in my opinion as under: 

1. Transfer data through some app or excel periodically.

2. Record all transactions in QuickBooks as well

3. Transfer sales figures in in Quickbooks through a journal entry on monthly or quarterly basis.

If I transfer sales figure through journal entry on monthly basis, what would be the journal entry i.e. which accounts to be debited and which accounts to be credited.