What is the tipping policy at Smashbox cosmetics to have your makeup done?

I have an appt. to get a makeover at Nordstrom at the Smashbox makeup counter and i just really want to know what i should tip or if i should buy their products to avoid the awkward situation of not knowing what to do.What is the tipping policy at Smashbox cosmetics to have your makeup done?
To the best of my knowledge, as a former Nordstrom employee, there is a 2 product minmum purchase for makeovers. I am not 100% sure since I never had my makeup done at Smashbox though. MAC, Two Faced, and Tony and Tina were all that way though. They usually tell you when you sit down. Either way, tipping is optional, but it would be very nice to tip $5 or so if you do not have to purchase anything.What is the tipping policy at Smashbox cosmetics to have your makeup done?
if you have an appointment then you are already paying for their services, you dont have to buy there products, and they probably arent going to try to sell them to you because you are already paying them for their services. Just tip 15-20 percent for their time and effort depensing on how well they do your make-up.