atime, tar and rsync

While doing some looking around on some of our production servers I was
noticing that all files are accessed pretty much every day. I know that
many of the files are not used by anybody, Does tar or rsync (both used
in parts of backups) moddify the atime? what else might modify the
atime on a standard setup. perhaps updatedb? Is there any way to get
system programs to not change the atime whenever they are just
catologing or backing up files?

Thanks
Bill Warner