Retail POS doesn't support Shopify's tipping feature. This is due to system limitations caused by the Shopify tips adding an extra additional payment line to all orders. Shopify orders that include tipping won't sync to Retail POS. 

To resolve the issue, recreate the sales directly in Retail POS. This insures that inventory updates and revenue are recorded in both Retail POS as well as Shopify.

1. In Retail POS, navigate to the Sell screen.
2. Add products included in the Shopify order.
3. (Optional) Add customer details.
4. Click Pay.
5. Type the correct payment amount, including the tip and process the sale.
6. This will close the sale and log it in Retail POS.