A second attempt (some whitespace remains):

sub ruler {
    my $n = ($_[0]+9)/10;
    (sprintf" "."%10s"x$n."\n",1..$n).'0123456789'x$n."0\n";
}
[download]

As a one liner (75 bytes):

perl -e'$n=(9+shift)/10;printf" "."%10s"x$n."\n%s0\n",1..$n,"012345678
+9"x$n'
[download]

John.
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