$inv->tax_included = $cart->tax_included;
$supp = get_supplier($cart->supplier_id);
$inv->tax_group_id = $supp['tax_group_id'];
$inv->tax_included = $cart->tax_included;
$supp = get_supplier($cart->supplier_id);
$inv->tax_group_id = $supp['tax_group_id'];