Free Shiping Per Category

I have a client that want's free shipping on orders over $100.00 of a certain category. Not the whole store.

Does anyone have an idea on how to do this?

Thanks

What happens on a mixed order where $100.01 come from this Category and $200 comes from other Categories?

Do you use Attributes with Prices or are all Prices on the Product Price (products_price) only?

What Shipping Modules do you use?

If the Order for this Category is > 100.00 ... should all of the other shipping methods turn off ... or ... should the Free Shipping be offered as a Shipping Option in addition to the other shipping methods?

The category that is at 100.01 I don't want there to be shipping on any of those items and the category that is 200 there is shipping on thoughs items still.

I don't have any attributes.

I also use the free shipping module for some of the items and weight shipping for some.

Do any of the Products in the Category for the Free Shipping when that Category is > 100.00 use Always Free Shipping?

No

(filler)

You are going to need to customize a check of the Products in the cart and test for the total of the Products that are in that category ...
$_SESSION['cart']->get_products()

will give you a list of the content of the shopping cart ...

You can then check the total based on the master_categories_id being the same as the categories_id that you want to give the Free shipping if over 100.00 ...