RCM Rate for Loading & Transport Charges

I am dealing with contract work from various department i have purchase material from unregistered dealers [ Sand, Jally, Etccc] for that i am paying RCM as per GST but i want to know for Transport charges i am paying 5% GST in RCM and taking the amount in ITC also but i want to know i want to pay 5% or 12% or 18%