The templates will show any taxes calculated by Shopify automatically.
If you are not seeing any taxes in your invoice, then we would recommend double checking your tax settings in the Shopify admin. You can do that on this page: https://shopify.com/admin/settings/taxes
Once taxes are setup in the Shopify admin, then they will automatically display during checkout, in emails and in the invoices.
Note: Shopify will not update old orders when you make tax changes, so only new orders will show the new taxes you have setup.