From CommerceV3 Docs
CV3 Documentation Resources
<?php
/*****************************************
* Tax Web Service
*
* input:
* $_GET['ship_state'] //ship state (abbrev. in all caps for us anud canada)
* $_GET['ship_zip'] //ship zip-code
* $_GET['bill_state'] //bill state (abbrev. in all caps for us anud canada)
* $_GET['bill_zip'] //bill zip-code
* $_GET['total'] //total order value (doesn't include tax exempt items)
* $_GET['shipping'] //total shipping
* $_GET['order_type'] //'retail' or 'wholesale'
*
* output:
* tax amount for order
*****************************************/
$tax = "0.00";
if ($_GET['ship_state'] == 'GA') {
$t_amt = ".06";
$tax += ($_GET['total'] + $_GET['shipping']) * $t_amt;
}
print $tax;
?>