VAT - Taxation of Sales - Geography

Sales made from a particular place to customers who are located in various states and the invoice is raised from the sales point. Will this be considered as inter-state sale. For eg: From Mumbai Sales Point it sold to customers who are in Hyderabad, Chennai, Poona, Nagpur & Chandigarh. Now this is sent by courier to them and the Tax Invoice generated will consist of their Address as mentioned above cities. While filing the Sales Tax Returns, should it be considered as Local Sales or Inter-State Sales ?

counter entry in waybills / Consignment note/ C forms needed to establish the sales as interstate. 

private couriers are usually not considered as evidence, coz they dont maintain any record.