Magento - Change Minimum order amount to Maximum Order Amount
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I'm trying to change the minimum order amount functionality found in System > Configuration > Sales > Sales > Minimum Order Amount to a 'Maximum Order Amount'

I'm hoping it will be as simple as changing a '>' to a '<' in the function but can't find the correct file.

[The purpose is that shipping to a particular country (which has it's own website) has to be below a certain dollar value otherwise customs duty, gst and other tariffs are paid. So I am trying to implement a maximum order value to keep all orders to this destination under that tier so that the customers don't have to pay unexpected fees]