AbleCommerce Shopping Cart Software

If the shipping for our store has 1-3 items the cost is $35 we can use the Vary by Quantity.
If the amount of items is greater than 3 we want to charge $10 per item how can we do this?

Do we have to customize the code?

Thanks
Mark

yes i think you need to write custom code to achieve this functionality because there is no such shipping method which provides facility to charge different shipping amount on different quantity.