There is a recording here of a good example word, "robar":
http://www.spanishdict.com/translate/robar
I think I understand the rolling or trilling of the initial "r" sound. I'm wondering about the final sound. Is it the same tongue position as the initial, but with a single "hit" (no rolling), or do I hear a rolling that is a little softer or more subtle, or something else entirely? Maybe it varies by region and accent.