I am sorry to share that currently there is not a way to show the tax percentage or amount per line item on an invoice. I must ask though outside of taxable and non-taxable do you have a use case that would require this? In general, once a tax rate is established it is the same rate across all taxable goods.
If you really need to vary the tax rate per item, I would suggest creating an item called Sales Tax which connects back to your sales tax payable account. Then I would create a bundle item that includes your product or service that is considered taxable along with the sales tax item. This would allow you to make the sales tax amount variable. I should warn though that this process can easily mess up your sales tax reporting if not managed correctly!
Here is a video I created some time ago about creating bundles:
I have managed to change the tax rate to just show 5% on the invoice, however it is mandatory to show the tax amount after it. I have attached a PDF showing the rules of the invoice when invoicing a Semi-government / government client in the UAE.
As you can see in the attachment, the "Tax Due" column example area needs to be added in our invoices.