Query for Requisition total Amount including Tax Amount

SELECT prla.line_num line_number,  
                       prla.item_description line_description,  
                       prda.distribution_num dist_number,  
                       prda.code_combination_id dist_code_combination_id,  
                       NVL (prda.nonrecoverable_tax, 0) nonrecoverable_tax,  
                       NVL (prda.recoverable_tax, 0) recoverable_tax,  
                       NVL (prda.nonrecoverable_tax, 0) + NVL (prda.recoverable_tax, 0)  total_tax,  
                       (NVL (prda.req_line_quantity, 0) * NVL (prla.unit_price, 0))  amount,  
                       prda.org_id,  
                       prda.DISTRIBUTION_ID  
         FROM      po_requisition_lines_all prla, 
                       po_req_distributions_all prda  
        WHERE    prla.requisition_line_id = prda.requisition_line_id  
        AND        NVL  (prla.cancel_flag, 'N') <> 'Y' 
        AND        NVL  (prla.modified_by_agent_flag, 'N') = 'N' 
    --  AND       prla.requisition_header_id = :1  
        ORDER BY prla.line_num, 
                       prda.distribution_num;