Not sure if anyone was aware of this but I found this article @ lifehacker showing how to add more then 5 fingerprints(up to 25) on the 5s. I have confirmed that this method works and now my middle, index and thumb on both hands can unlock my phone using only 2 of the available 5 slots! This definitely makes it much more convenient then it already was. So far the scanner has worked flawlessly reading all 6 fingers with no issues as of yet. Very simple process to do..here is the article.
Register More Than Five Fingerprints on Your iPhone 5s
Register More Than Five Fingerprints on Your iPhone 5s