force uppercase in Marketpress coupon code box

I forced uppercase in the coupon code box with CSS – but I realized this actually made the problem worse because it doesn’t actually make the font uppercase – just it’s presentation – so customers THINK it’s uppercase.

What do I hook into to force this with a hook?

We have custom code that when you make a new coupon in marketpress it syncs with stripe – but it syncs only a case-sensitive version and does not allow you to make a lowercase brother to the code… so I just need to force ALLCAPSALLTHETIMEEVERYWHERE