I am on the Digi Prepaid LiVE and Digi Smart Prepaid rate plan, where Digi to Digi calls are charged at RM0.30/min. Will the 7th min be rounded down to RM2?

No, we will still charge the full RM0.30/ min, hence you will need to hit RM2.10 to be eligible for the FREE all-network Calls offer.