Did you have a specific order that didn't have the taxes applied properly? I'd love to get to the bottom of this for you.
I took a look at your tax settings and your shop is set up to include taxes in your prices:
I also did a test order with a discount added and the taxes were added correctly:
Please feel free to email me directly with any order information you'd like to me take a closer look at.
Shopify Guru | email@example.com