I know there are other instances of this questions strewn about on this stack, but I haven't found a clear and defined answer.
I currently have a free shipping shopping cart rule created. I have to use this method instead of the free shipping section under the config/shipping section of the admin since I have to exclude Hawaii & Alaska from receiving the free shipping. The rule is set to work on USA based orders with a subtotal of $75 or greater. Works perfectly fine, however, if someone also uses a discount code that puts them below the $75 threshold, it still applies the free shipping.
ex. Customer has a subtotal of $80 and then applies a 10% discount code, putting their subtotal at $72, magento still gives them free shipping since it's looking at the subtotal pre-discount.
I'm using 1.9.1 currently, how can I fix this easily? I'd rather not touch any core files, since I don't want to have to fix this anytime Magento gets upgraded.