Advance tax

Can advance tax be paid only on 15 of Sep, Dec and March. Can one pay adv tax every month to save on penal interest.

I have to pay total tax of Rs 100000. I could pay Rs 20000 only on 15 Sep 2014 while I should have paid Rs 30000 i.e., 30% of Rs 100000.

On dec 15, I could make payment totalling to Rs 40000. It should have been Rs 60000 (60% of Rs 100000).

Now can I pay Rs 20000 each in January, February and March. If yes, how penal interest will be charged?

Kindly clarify.

Thanks.