Gains/losses from stock dealings - calculations

Dear Experts,

While calclulating Gains/Losses from stock dealings, we generally deduct/add all additional costs like brokerage, service tax, STT etc. I believe STT and Service Tax etc can't taken as costs and only brokerage needs to be get deducted/added if we want to be 100% correct in our tax calculations.

So when I did a re-calculation of one of my deals without STT and Service Tax, my costs came to be nearly 89% of my initial costs. So my gains got increased and losses got decreased!

Please clarify on this subtle aspect of IT calculations.

Regards,

Harsha Vardhana R