Service tax on online marketing business supprt

Dear Sir I am doing work for US company. Basically in india we manage US website. we support the us customer & make the payment at US website for product & serivces. For this US company give us a fixed margin like that 10 to 25%. This money we receved in our account in india after conversion. Kindly advise this service comes in which head & it will be taxable uder service tax act or not. Please help.