eCart object - applying Discounts
I tried playing around with the eCart object to implement a discount, but had no success. The fact is I simply don't know how to start to make it work. The discount I need to implement is for bulk orders. So, for example, if the order is above 5 items, then there's a 30% discount, if the order is over 10 items, then there's a 50% discount.
Is there a step by step instruction sample that explains something similar to this?