how much to tip at Christmas?

My wash and blow dry is 17$ and I give her 23$ total ... she used to charge me 15$ and then raised it but I still pay the same, her tip just went down .... and I give the washing hair girl 2$ ....
I give about 20$ as a tip when she colors my hair and blow dries it ... that comes to 62$ (color etc is 40$ and 2$ tip for hairwasher and the rest is for her ... she raised that $5.00, so whatever is left over is her tip) ...

I guess I shall give her 25$ for Xmas ... I think I gave 30$ last year and gave her a Movado watch (I had gotten it for my daughter but it was too tight, the hairdresser is very little) but i don't think she realizes what the watch is worth ...