I'm not quite sure what you are after, but this may get you going. Note the technique of including data in a __DATA__ section in the script to facilitate testing - especially by other people.

use strict;
use warnings;

my @st_n;

while (defined (my $line = <DATA>)) {
    my @array = split(/,/ , $line);
    my $test = @array;

    next if $test < 6; # Skip lines that don't have at least 6 fields
    
    my $store_number = $array[1];
    
    print "$array[5] offers and $test is number of elements\n";
    if ($array[5] =~ /0000000/ || $array[5] =~ //) { # the 2nd part is
+ obviously wrong
        print "$store_number is not BCE Store\n";
    } else {
        print "Store # $store_number\n";
        push(@st_n, $store_number);
    }
}

__DATA__
20060819,02159,045488061,00 ,0000118,0000000,0000000,0000118,0000000,0
+000000,Zachary             ,G
20060819,02159,045775830,00 ,0000649,0000028,0000000,0000649,0000028,0
+000000,
,
20060819,02161,023416381,09 ,0000034,0000000,0000000,0000034,0000000,0
+000000,Erinne              ,H
[download]

Prints:

0000000 offers and 12 is number of elements
02159 is not BCE Store
0000028 offers and 11 is number of elements
Store # 02159
0000000 offers and 12 is number of elements
02161 is not BCE Store
[download]