Checkbox for include tax in cart page

Some customers do not want to pay taxes. I want to add an option to pay tax in the cart page like a checkbox that customers want to pay taxes or not.

on the checkout page, add your checkbox, name it taxabke, give it a checked value of 1.

<input name="taxable" type="checkbox" id="taxable" value="1" />

on the confirm page, near thew bottom, you will see a collection of hidden form elements, add a new hidden form element named taxable that will capture the value posted from the checkout page:

<input name="taxable" type="hidden" id="taxable" value="<?php echo((isset($_POST["taxable"]))?$_POST["taxable"]:"") ?>" />

Go to the server behaviors panel and create a new Set Session Value behavior. Click the plus button, and select eCart -> General -> Set Session Value. Set the name to taxable. For the trigger and value, click the lightning bolt and select the taxable hidden form element.

in the tax rule, add an additional trigger:
"Based on session variable value"
If the session variable "taxable" is "=" a value of "1"

this will charge tax only if they check the taxable check box.