Some girls only do real massage. You can ask them whether she will do extra before the massage begin. Mostly they are.
This tariff really depends on your negotiation and of course the girl. If the girl likes you, you might get paid haha. If she doesn't like you, she won't do it even you give her $^6.
http://www.indoholiday.com/2008/11/kuta-timur-resort-massage-and-spa.html