Hey there, keath.
Thanks for getting back to us. I want to share some insights about your invoice concern.
Right now, setting up the service item to a percentage rate is unavailable in QuickBooks Online. You'll need to enter the desired amount manually on every invoice.
We value our customers with what they need and what works best for their business. The feedback process will help us determine what feature/option you need for the product.
You can send your feedback directly to this link:
https://feedback.qbo.intuit.com
The Community team looks forward to any help you need. Just let us know by posting a comment below.