I see that you have already enabled sales tax settings. The next thing you can do is create the invoice in the UI and then load it through the API as Matt suggested. Assign some tax to the invoice and Read it using API explorer. THis will give you an idea as to what is expected in the lines. This will definitely help you out with the correct tags you need to set.
Alternately refer to the docs with example request here- https://developer.intuit.com/docs/api/accounting#/complex-data-types
Global tax model- https://developer.intuit.com/docs/0100_accounting/0300_developer_guides/global_tax_model