use List::Util 'max';
my $selected = max grep { $find >= $_ } @array;

##</code><code>##

# Find the largest number in @array
# that is <= $find and put it in $selected
my $selected;
foreach my $number ( @array ) {
    $selected = $number    if $find   >= $number
                          and $number >  $selected;
    last if defined $selected and $selected == $find;
}