$nearest=10;
$price=int(($price+$nearest/2)/$nearest)*$nearest;
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This is parametric on the "granularity"

UPDATE: and it also works if $nearest is less than 1 (say you want to round to the nearest 0.5)

-- 
        dakkar - Mobilis in mobile

sub round
{
    my ( $price, $round ) = @_;
    return int(( $price / $round ) + 0.5 ) *  $round;
}

print round( 418, 10 ), "\n";
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The round subroutine takes two parameters, the number to be rounded and the nearest value to which you want it to be rounded to.

perl -le 'print+unpack("N",pack("B32","00000000000000000000001001000001"))'

  use Math::Round qw(nearest);

  $quote = 418.00;
  $price = nearest(10, $quote);
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I don't know if it's important, but this implementation deals properly with negative numbers. From Math::Round:

sub nearest {
 my ($targ, @inputs) = @_;
 my @res = ();
 my $x;

 $targ = abs($targ) if $targ < 0;
 foreach $x (@inputs) {
   if ($x >= 0) {
      push @res, $targ * int(($x + $half * $targ) / $targ);
   } else {
      push @res, $targ * POSIX::ceil(($x - $half * $targ) / $targ);
   }
 }
 return (wantarray) ? @res : $res[0];
}
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Cheers,
Matt

Be aware that in certain situations it's considered bad form to pretend to maintain precision at the hundredth level when you've just rounded the nearest 10. You might want to clarify whether '418.00' rounds to '420.00' or '420'.