[CentOS] ls -lrt reversal

My CentOS box with:
  $ uname -r
  2.6.18-164.6.1.el5

gets the file order wrong with:
   ls -lrt *
.
Two files that were last modified in the same
second are shown in order that is the reverse
of the order in which they were actually last
modified.  Note also that the later file was
first created after the earlier file was last
modified.

Is the precision of this only to the second?

Mike.