Yes, you can use two or more than two existing sales tax items to create a group.
- Click on Setup under Preferences in the Sidebar
- Click on Sales Tax Group under Billing & Invoice
- Click on +Add Sales Tax Groups and you will get a popup to add details
- Enter Group Name, Group Description and click on +Add Sales Tax item and select the sales tax items from the popup and click on Add Item.
- Group Rate will be calculated automatically depending upon your selection of sales tax items
- Click Save and Close and your Sales Tax Group is created