On my card there is a Foreign Currency Transaction Fee in which the conversion rate is marked up by 3.5% - too little to be bothered about.. In fact I had never bothered to look up the exact quantum till today

though I knew there is some additional charge.
This charge may be different on different cards. Please check your card's website for tariff details or call your helpline and ascertain the quantum for your card.(unless of course an ICICI card holder here can give the exact quantum)