Price sorting with items on sale

I have 2 tax classes, one with markup and one without.

When I load a special I use the tax class without markup.

My problem is the sorting uses the prices before the tax class gets applied and not the total price.

How can i get it to sort using the total price after the tax class has been applied?

Thank you so much

https://dialatyre.co.za/?s=&post_type=product&trizzy_search=advanced&trizzy_pa_width%5B%5D=155&selectItemtrizzy_pa_width%5B%5D=155&trizzy_pa_height%5B%5D=70&selectItemtrizzy_pa_height%5B%5D=70&trizzy_pa_size%5B%5D=r13&selectItemtrizzy_pa_size%5B%5D=r13