Buy more and save promotion

We want to do a Buy More and Save promotion with 3 shows and one promo code. i.e. Buy 1 show save 10%, buy 2 shows, save 25% and buy 3 and save 35%.  I would like to make this happen so patrons can buy online and over the phone/in person.  We use TNEW and I use pricing rules a lot now for a single offer, but I am wondering if anyone has made this work with multiple level offers before.

I am in the middle of testing some ideas, but would love any input that could make this process go faster.  

Thank you in advance.