There was a following problem:
All my products have tax.
After the transition from the cart to the page checkout tax return nulled. When we return to the cart tax will be nulled.
One Page Checkout Extensions use for the cart.
How to fix it? Thanks.
Go to Solution.
Just an idea - when you goto the Checkout page is another country selected as the default and the plugin you are using is using that country to calculate the tax rate?
This sounds like it might be better suited to contact the plugin developer since this is obviously not default Magento behaviour.