On the back of a US one hundred dollar bill the hands of the clock point to four-ten. What does that stand for?

The time is approximately 4:10. Although the time is not readily identifiable to the naked eye, it may be verified if examined under twenty-fold magnification. There are no records explaining why that particular time was chosen.

http://www.panix.com/~clay/currency/facts.html

Most sites say the time is 4:10 but a few dispute this and say it is 2:21. The following gives an explanation as to why: -

The United States government has been issuing official certificates for many years showing that the U.S. horoscope actually has Scorpio Rising. The certificates are in the form of the one hundred dollar bill, with founding father Benjamin Franklin on the face side, and the historic scene of Independence Hall, the location where the Declaration was signed, on the reverse side. The clock on the Independence Hall bell tower shows very clearly a time of 2:21 PM. Is this just a coincidence? Or is this acceptable evidence that the historic moment is being commemorated on the one hundred dollar bill?

Then, here's some numerological reasons why 2:21 PM makes sense. This time puts the Sun at 13 degrees 13 minutes Cancer. The number 13 resonates powerfully through all of early America's history. Thirteen original colonies make up the foundation of this country. The Great Seal, inscribed on the back of the {$1} bill, features the cosmic significance of 13 in many different ways, including: 13 stars above the Eagle, 13 stripes on the Eagle's shield, 13 olive branches in the Eagle's right claws, 13 arrows in the Eagle's left claws, 13 steps on the pyramid, and 13 letters in the motto E Pluribus Unum.
http://www.astrodatabank.com/NM/USA.htm

The hands on the clock are obviously different lengths with the longer hand pointing between the IV and the V. This would make that hand the minute hand. This is seen with a larger magnification by the length of that hand alone extending out of the inner circle. The other hand appears to point to the II but does not extend past the inner circle which makes it the shorter hand and also the hour hand. Review the reverse image posted on wikipedia which is a print of the 2003 A series. Also, note that the longer hand, minute hand is almost half way between the “V” of the IV time and the “V” of the V time. It is slightly closer to the IV which would suggest a time of 2:22 or 2:23. According to the Bureau of Engraving and printing the time is 4:10 with no reason why this time was chosen.