Currently Ajio is running a offer on ICICI credit cards wherein you can get 10% discount on gold coins (max Rs 1000)...Net cost is below market rate...You may take advantage
As far as I know, it's not 5% extra it's just that you can pay upto 5% using supercoins. So if someone doesn't have any supercoins then he may not use it.
Correct me if I'm wrong.