Service tax on new service & rare

Sir , if one builder/developer construct one G+lV st.building,on which ground floor he make some shop for selling of glossary items to fullfil daily needs of local people.Plan sanctioned from local authority, but no completion certificate has been issued till the time of sale.at the time of sale of those shop what percentage of service tax he charge from customer?Is this service taxable under " construction of commercial complex" or under " construction of residential complex"? If it is fail under the catagory of commercial service, any abartment available under service tax? As the service provider does not segrigrate labour & materials to construct those shop.