Add note on python round().

libraries/base/common/python/try_round.py

@@ -40,6 +40,10 @@ import matplotlib.pylab as plt
 Usage:
 > python try_round.py -h
 
+Note:
+. For values exactly halfway between rounded decimal values, NumPy rounds to
+  the nearest even value. Thus 1.5 and 2.5 round to 2.0, -0.5 and 0.5 round
+  to 0.0, etc.
 """
 
 import argparse