National Highways Authority Of India [NHAI] — Toll Plaza Issue

Vehicle Number : TN65U5576. I have crossed Kappalur Toll Plaza, Madurai Now. I have a fastag balance of 195 Rupees. The Toll plaza people said Amount will not be debited if the balance is below 200 Rupees. I have paid a cash of 190 as cash to cross the toll plaza. I have balance below 200 yesterday also but amount for debited in some other toll plazas yesterday.
Please confirm if there is any rule by GOVt that we should maintain amount more than 200 Rupees