Some brain storm !
I check this out, and I we can add code to show price before tax in case tax is included in the price.
Because AbanteCart has more features than Opencart, there are few things we need to consider.
1. I do not think it make sense to show price before tax in product listing. Comments?
2. In product details page, base price can be shown before tax, but there is a challenge for product options.
It will be confusing if all option will be shown with before tax (not clean UI)
How about showing only total price (after discounts and options) with tax and before tax ?