I corrected the line that you mentioned and it calculates the tax But the tax amount is very higher than the price...funny (certainly I did some mistakes somewhere...).
At the top you will see:
tax rate: [9.750]
from rs: [9.750]
Is that mean that the tax is set to be calculated 2 times?
Please see the screen shot:
I also get this error message when I click on "Check out with PayPal" button in checkout page: