Hello,
Mop up rounds are comducted when some seats remain vacant in government or private colleges in a state after rounds of counselling.
Fees for a seat through mop up round is same as admisson through the other two rounds.
For government colleges it is usually 20-70k Rs and for private colleges it is usually 4-10 lakhs.
Bit for management quota seats in private colleges fees is more than 40 lakhs.
Follow this link for more
https://www.google.com/amp/s/medicine.careers360.com/articles/mbbs-fees/amp
Good luck