Why is my tax override function not working correctly in Ontario?

I’m having the same issues for my own Shopify bookstore, but one thing I thought of could be to just provide a refund to the customer for the amount that they were overcharged for the taxes on shipping. Admittedly, It would be a little tedious to have to do this for each and every order, but it might be a simpler solution than tracking the overcharged amount and then remitting to the appropriate province? Curious to get other people’s thoughts on this as well!