Website is currently set up to sell coffee to the United States only with a flat rate shipping charge. Client would like to offer free shipping on orders over qty. 4 but also include Canada and Mexico. Only orders being delivered to the Untied States could be for less than qty.4. Wondering how to set this up? I know there can be coding to enable shipping minimums and I could change the shipping zones, but then how can I keep the ability for small orders with chargeable shipping to be able to be delivered in the US.