How much do i tip for a deal that i got on a facial and massage?

[Love to dance]

So i got a deal for a 1 hour massage and 1 hour facial at $25 each. The normal price on the massage is $50 and the normal price on the facial is $85. Total $135 which is $27 on 20% tip.
Do i tip 15-20% on the normal price or should i tip anymore because i got a good deal? Ive heard that when a salon gives a deal to a client the therapist normally relies on tips for their wage. is this true? If so id feel bad to only leave that much just because i got a good deal. Although that defeats the purpose of a 'deal' could anyone shed some light! thanks!!