Does Quickbooks recognise Tips?

When tips are enabled in the client portal, a Tip Button is added to the Account Summary screen enabling your client to pay a Tip in addition to the amount shown on their invoice. 

How are tips shown in Pet Sitter Plus and synced with QuickBooks Online? 

Tips are recorded as non-taxable items in both systems.

In Pet Sitter Plus, a tip is added to an invoice:

In QuickBooks Online, the tip is shown as a line item on the invoice.

Note: If the tip is subsequently deleted in Pet Sitter Plus, then it is also deleted in QuickBooks following synchronization.

Info: Further reading....
Sync Transactions in QuickBooks
Sync Refunds with QuickBooks
Sync Write Offs with QuickBooks
What happens with Voided Invoices in QuickBooks?
Sync Invoices with QuickBooks