tracking it down to a piece of custom code maybe - I can't see the problem:

/*------------------------------Whole sale customer code-------------------*/
$customer_whole_obj = $db->Execute('select `customers_whole` from `'.TABLE_CUSTOMERS.'` where `customers_id` ='.$_SESSION['customer_id']);
$customer_whole = $customer_whole_obj->fields['customers_whole'];
if($customer_whole == 4){
$_SESSION['customer_level'] =4;
//print_r($_SESSION);
if($_SESSION['payment'] == 'paypalwpp' || $_SESSION['payment'] =='cc'){
$this->info['charges'] = 2.5;
$this->info['total_without_charges'] = $this->info['total'];
$this->info['charges_amt'] = ($this->info['total'] * $this->info['charges'])/100;
$this->info['total'] = $this->info['total'] + $this->info['charges_amt'];
}
}
/*------------------------------End Whole sale customer code-------------------*/