With help from Jive Support, I was able to achieve the effect I needed. Since this question has not been answered, I'll share my findings so it may benefit someone down the road.
When I started, I knew that HttpReferer is an optional field. What I didn't know was that the browser drops the HttpReferer field when it directs requests from https to http. The mechanism works if you are navigating from http to http, https to https or http to https but not https (such as my hosted Jive site) to http (most retailer websites). This is why the http storefront link worked when originating from (http) cnn.com. Luckily, most of my customers have their https protocol active. I was able to post their https retail links from my Jive site and have users click on them to navigate to shop. In the storefront, we were able to evaluate HttpReferer and only honor the coupon code when the referrer condition is met.
It is also important to keep in mind that HttpReferer will be blank if someone bookmarked the storefront URL or manually cut and paste the URL. That is perfect for my purpose since I only want the coupon code to work when someone originates from my Jive site.