At the moment, there is no special key to remove the coins from the counter. The ticket key commands are intended to simplify things (e.g. if you're unfamiliar with the tickets or don't want to do mental arithmetic), so what could this function simplify? It's just clicking on the coins and they're gone. Otherwise you wouldn't even have to look in the direction of the passenger which is quite unrealistic while selling a ticket.
So I cannot promise if this function will be included.