Got this from their FAQ section. Hope it answers your question
I paid for a meal at a restaurant with my Visa Card. The authorization on my Account for my meal purchase is different than the amount I spent. Why is this?
When you purchase a meal at a restaurant with your ePassporte Visa Card, your transaction is authorized for the amount of the meal plus an extra amount (to allow for a potential gratuity). These authorizations are removed from your Account when the Merchant settles the actual amount spent at the restaurant, usually in 7 to 10 days.