foreach $header (@$headers) {
   ...
}

##</code><code>##

use strict;
use DBIx::XHTML_Table;

my $table = DBIx::XHTML_Table->new("insert db credentials");

$table->exec_query("
     select  data_name, sum(data_value)
     from dwhs.store_reports
     where   report_type = ? 
     and     timestamp >= sysdate - ?
     group by data_name
",[$list_name,$day_list]);

$table->modify_tag(table => {
   border      => 3,
   cellspacing => '0', 
   cellpadding => '0',
   width       => '100%',
});

$table->modify_tag(td => {
   bgcolor => '#CCCCCC',
   align   => 'center',
});

print $table->get_table();