Tex Exempt / Wholesale Group without buying yet another module

[dsgnmind]

I really don't need another module and the bells and whistles that go along with it. I really just need a code mod to make one group be tax exempt. Using 1.5.3.1

 

I've tried this:

class Tax extends TaxCore
{
/**
* Returns the product tax
*
* @param integer $id_product
* @param integer $id_country
* @return Tax
*/
public static function getProductTaxRate($id_product, $id_address = null, Context $context = null)
{
/*if ($context == null)
 $context = Context::getContext();
$address = Address::initialize($id_address);
$id_tax_rules = (int)Product::getIdTaxRulesGroupByIdProduct($id_product, $context);
$tax_manager = TaxManagerFactory::getManager($address, $id_tax_rules);
$tax_calculator = $tax_manager->getTaxCalculator();
return $tax_calculator->getTotalRate();
*/
	    if (is_numeric($id_address)) {
					    $address = new Address((int)($id_address));
			    // get customer groups to check for tax exempt group
			    $groups = Customer::getGroupsStatic((int)($address->id_customer));
			    //var_dump($groups);
			    foreach ($groups as $g) {
							    $query = "SELECT name FROM ps_group_lang WHERE id_group=$g AND id_lang=1";
							    $groupname = Db::getInstance()->getValue($query);

							    if (strtolower(substr($groupname, 0, 9))=="wholesale"){
									 return 0;
									 }
							   }
					   }
	    $context = Context::getContext();
 $address = Address::initialize($id_address);
 $id_tax_rules = (int)Product::getIdTaxRulesGroupByIdProduct($id_product, $context);
 $tax_manager = TaxManagerFactory::getManager($address, $id_tax_rules);
 $tax_calculator = $tax_manager->getTaxCalculator();
 return $tax_calculator->getTotalRate();		
}

 

AND this

static public function getApplicableTax($id_tax, $productTax)
{
    global $cart, $cookie, $defaultCountry;
    $noTaxGroup =3; // Group number that is tax exempt
    $customer = new Customer($cart->id_customer);
		    if ($customer->isMemberOfGroup($noTaxGroup)) {
		    return 0;
    }

 

to no avail.

The second option seems more what I'm looking for because I don't see how the tax exempt group will ever change. But that code was for 1.4

 

Please help! Thanks!