Tax Exempt by Customer Group

[lunabug]

I found this thread http://www.zen-cart.com/showthread.p...Customer-Group and followed what was suggested and my Tax Exempt group is still having taxes added.

This is from my functions_taxes.php file

 function zen_get_tax_rate($class_id, $country_id = -1, $zone_id = -1) {
    global $db;

    // added to make groups tax exempt. See also includes/modules/order_total/ot_group_pricing.php  
        if(isset($_SESSION['tax_exempt'])){
              return 0;
        }
    // end tax exempt
    ... 

This is from my ot_group_pricing.php file

  function get_order_total() {
    global  $order;
    $order_total_tax = $order->info['tax'];
    $order_total = $order->info['total'];
    if ($this->include_shipping != 'true') $order_total -= $order->info['shipping_cost'];
    if ($this->include_tax != 'true') $order_total -= $order->info['tax'];
    if (DISPLAY_PRICE_WITH_TAX == 'true' && $this->include_shipping != 'true')
    {
      $order_total += $order->info['shipping_tax'];
    }
    $taxGroups = array();
    foreach ($order->info['tax_groups'] as $key=>$value) {
      if (isset($_SESSION['shipping_tax_description']) && $key == $_SESSION['shipping_tax_description'])
      {
        if ($this->include_shipping != 'true')
        {
          $value -= $order->info['shipping_tax'];
        }
      }
      $taxGroups[$key] = $value;
    }
    $orderTotalFull = $order_total;
    $order_total = array('totalFull'=>$orderTotalFull, 'total'=>$order_total, 'tax'=>$order_total_tax, 'taxGroups'=>$taxGroups);

    // added to make groups tax exempt. See also includes/functions/functions_taxes.php
        $groupname=$group_discount->fields['group_name'];
        if(eregi("Tax Exempt",$groupname)){$_SESSION['tax_exempt']=TRUE;}  
    // end tax exempt

    return $order_total;
  } 

The name of my group is Wholesale (Tax Exempt)

I've tried to printout the session variables using this but tax_exempt is not listed:

<!-- Print Session Variables BEGIN -->
<?php
    session_start();
    foreach ($_SESSION as $key=>$val)
    echo "Key <b>".$key."</b> has the value of: <b>".$val."</b><br>"
?>
<!-- Print Session Variables END -->

What have I done wrong or omitted?