Update - I paid 15%.  Felt kinda guilted into it; when the credit card was swiped, I had the "option" of adding a tip.  It came to a gratuity of a little over $30 on a six-treatment package, so not the end of the world, and the tech who performed the first treatment was extremely patient with me and certainly earned the money.

On a related subject: my god, that laser f**king stings a million times worse than I ever expected it to!

^^ Heh Heh Heh.

The mustache area hurts the most, even on the 2nd treatment it's just as bad as the first.

Die beard die!!!!