Items that are set up as a percentage in QuickBooks Online will sync over with a rate that is a dollar amount in Bill.com. If this needs to be a percentage (%), edit the item in Bill.com to the correct percentage once the item syncs successfully. 

1. Hover over the gear icon, click Settings
2. Under Accounting, click Items
3. Click the Item name
4. Click the edit icon
5. Update the Price/Rate field
6. Click Save