How do coupons affect reward points?

Coupons don't seem to affect the amount reward points issued. That doesn't seem right. For example, a customer just bought $5 of products, used a $5 coupon to reduce the cost to zero. That customer still earned reward points for the free products.

I want reward points reduced by the coupon amount. Can that be done?

Thanks,
David Bal
www.DJMagicCards.com