Sorry to bring this up after so much time last time i just totally edited and practally manually made the tax calculation modified so much ecart that was a pain later on for any update to the page. So now i will try to do this the correct way.
Ok storing the taxRate in a session is easy but how can i tell the grand total to use that tax rate saved in a session, i see that in the eCart Merchandising Rules theres an option for if session exist ok so far until here or also using total number of items > 0 so far the last step is what im not sure what to do.
On other places i had the tax setted to : Cart Taxeble total --> Times --> 0.12 (since the tax is at 12% for that other job) but the one im making right now the country changes the tax rate every year so i have to make it dynamic, so on that last part of the rule what should i pick im guessing based on a column subtotal and picking TaxRate but after that time? minus? i dunno from here any help please?