I am talking about NITs. Because if you have got good rank in jee main than you will definitely get seat I'm it.There is 100% Tution fees concession. But you have to pay other fees per semester that include the wifi you used in Institute, Books fees , exam fees etc. This fees is 6999 in NIT Jalandhar, 13000 in MNIT JAIPUR. Its vary in every NITs. If you want to stay in hostel than you have to pay the full fees of hostel & mess there is no concession in it. There are scholarships for SC/ST candidate which can easily help you to pay your other fees of the college.

The above rule is follow in most of the institutions in India. They give you full Tution fees concession but you have to pay other fees in most of the engineering colleges in India. 

Don't worry about fees there are many scholarships available. If you got good rank than you can easily get loan also. But most of the times scholarships amount is enough to pay the fees.some scholarships also pay hostel fees & mess fees also.