In April, I brought about $15 in pennies on my carry on because it made the suitcase weigh too much. And they looked at it in the x ray like I was nuts. But they didn't search it and waved me through. Your results may vary.
Yeah I just went through the x ray a few days ago with about $30 face of silver, some wheaties, a box of foreign coins, 17 proof sets and four coin books. They let me through after taking a quick peek at my bag.
Personally I wouldn't carry more than a few rolls as to not attract too much attention. Unfortunately that severely limits the kind of hunting you can do when traveling via air. No such limitations on road trips!