SELECT  `main_table`. * , (

SELECT COUNT( * )
FROM sales_flat_order_item AS sfoi
WHERE sfoi.order_id = main_table.entity_id
AND tax_percent = 5.5000
) AS totalprod55
FROM sales_flat_order AS main_table
INNER JOIN  `sales_flat_order_address` AS  `customer` ON main_table.billing_address_id = customer.entity_id