Formula for Tiered pricing with various pricing matrix

Hey,

I am trying to work on calculating revenue based tiered pricing which on various types of pricing matrix. Please help me what formula will help me calculate this.

Pricing Modal Volume Price
Flat Pricing Any volume 0.15
Step Basis 0-1000 0.15
1001-2000 0.14
2001-10000 0.13
10001 - Above 0.11
Slab Basis %age discount 0-1000 0.15
0-2000 0.15-10%
0-3000 0.15-15%
3000 - Above 0.15-20%
Volume based free units 1000 0.15
1001-2000 0.15 100 Units free
2001-3000 0.15 200 units free

Looking for help in terms of defining formula without using VBA.