Try this change instead:
Code:
// adjusted count for free shipping
$item_total_count = $total_count - $_SESSION['cart']->free_shipping_items();
global $cart;
$chk_flowers = $_SESSION['cart']->in_cart_check('master_categories_id','14');
if ($chk_flowers > 0) {
$chk_flowers = 15.00;
} else {
$chk_flowers = 0;
}
$this->quotes = array('id' => $this->code,
'module' => MODULE_SHIPPING_ITEM_TEXT_TITLE,
'methods' => array(array('id' => $this->code,
'title' => MODULE_SHIPPING_ITEM_TEXT_WAY,
'cost' => (MODULE_SHIPPING_ITEM_COST * $item_total_count) + MODULE_SHIPPING_ITEM_HANDLING + $chk_flowers)));