...snip...
<input type="checkbox" value="5100" name="buscodes" >5100 Industrial Manufacturers<br>
<input type="checkbox" value="5200" name="buscodes" >5200 Industrial W & D<br>
<input type="checkbox" value="5210" name="buscodes" >5210 Internet Distributors<br>
<input type="checkbox" value="5300" name="buscodes" >5300 Business Equipment M & D<br>
...snip...

##</code><code>##

foreach my $val (qw(2800 2820 2830 2840 2850)) {
	$m->field('buscodes', $val);
}