@baijumohan,
Please take a look at the following thread:
This provides a solution to the same incorrect totals problem, and explains in pretty good detail the logic behind the solution.
If you still have questions after going through this, just give a shout.
I hope this is helpful.
https://forum.enterprisedna.co/t/why-your-total-is-incorrect-in-power-bi-the-key-dax-concept-to-understand/5108
https://forum.enterprisedna.co/t/fixing-errors-with-your-totals-efficiently/4948