In the data you provided there is no duplicate keys, so no adding will happen. The key is the concatenation of $subc and $state and this combination creates unique keys for your data.
See below where I integrated you MAP and REDUCE into on loop. 

use strict;
use warnings;

my %worth;
while ( <DATA> ) {
        chomp;
        my( $txnid, $date, $custid, $amount, $productc, $subc, $city, 
+$state, $mode ) = split /,/;
        $worth{"$subc.$state"} += $amount; # REDUCE
}
while( my ( $key, $value) = each %worth ) {
        print "key: $key, value: $value\n";
}

__DATA__
00000000,06-26-2011,4007024,040.33,Exercise & Fitness,Cardio Machine A
+ccessories,Clarksville,Tennessee,credit
00000001,05-26-2011,4006742,198.44,Exercise & Fitness,Weightlifting Gl
+oves,Long Beach,California,credit
00000002,06-01-2011,4009775,005.58,Exercise & Fitness,Weightlifting Ma
+chine Accessories,Anaheim,California,credit
00000003,06-05-2011,4002199,198.19,Gymnastics,Gymnastics Rings,Milwauk
+ee,Wisconsin,credit
00000004,12-17-2011,4002613,098.81,Team Sports,Field Hockey,Nashville 
+ ,Tennessee,credit
00000005,02-14-2011,4007591,193.63,Outdoor Recreation,Camping & Backpa
+cking & Hiking,Chicago,Illinois,credit
00000006,10-28-2011,4002190,027.89,Puzzles,Jigsaw Puzzles,Charleston,S
+outh Carolina,credit
00000007,07-14-2011,4002964,096.01,Outdoor Play Equipment,Sandboxes,Co
+lumbus,Ohio,credit
00000008,01-17-2011,4007361,010.44,Winter Sports,Snowmobiling,Des Moin
+es,Iowa,credit

[download]

In reply to Re^3: Create a Hash Dynamically and add the values of same key by hdb
in thread Create a Hash Dynamically and add the values of same key by rahulruns

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