additional shipping option to our custom zen cart shipping module

We currently have 4 custom shipping options in out zen cart shipping module. they are as follows: #1 <$100 material value = $10 Flat rate >$100 material value = 10% of material total #2 Charge actual shipping based on items weight and box size #3 <$150 material value = Charge actual >$150 material value = FREE #4 Free shipping **Note** The shipping rules for the items are determined by a field in the item table for each item. If there are 2 items on the order and one item has a #1 shipping rule and one item has a #2 shipping rule both shipping totals are added together to come up with a shipping total. THIS IS ALREADY PROGRAMMED AND WORKING FINE We would like to add in a 5th new rule that works as follows: <$150 material value then charge a flat rate of $15 if >$150 material value then charge $15% of the material total. This should be a very simple coding project as the majority of the work and coding is already complete. We just need this 5th option added in ASAP. Attached is the code that is currently in place for the shipping module.