Limbic~Region's solution is fine; I'm throwing mine in just for a slightly different point of view.

use strict;
use warnings;

my( $company, $co_id );
my $item;

local $, = ",";
local $\ = "\n";

while (<DATA>)
{
        next unless /\S/; # ignore blank lines
        next if defined $item && /^ *Total \Q$item\E /;
        next if defined $co_id && /^ *Total \Q$company:$co_id\E /;

        if ( /^ *(.+):(\S+) *$/ )
        {
                ( $company, $co_id ) = ( $1, $2 );
        }
        elsif ( /^ *(\S+) *$/ )
        {
                $item = $1;
        }
        else
        {
                my( $date, $person, $value ) = /^ {10}(.{10}) {5}(.*) 
+(\S+)/;
                $person =~ s/ +$//;
                $date =~ s/^ +//;
                print $co_id, qq("$company"), $item, qq("$date"), qq("
+$person"), $value;
        }
}

__DATA__
        Slate Enterprises, Inc.:2001050.01
          104
           1/24/2002     Johnson, Dean A.                         10.0
+0
           1/24/2002     Botwell, Michael J                       10.0
+0
          Total 104                                               20.0
+0

          302
           1/25/2002     Beers, James T.                           2.5
+0
           1/28/2002     Beers, James T.                           4.0
+0
           1/29/2002     Beers, James T.                           1.0
+0
           1/30/2002     Beers, James T.                           0.5
+0
          Total 302                                                8.0
+0

        Total Slate Enterprises, Inc.:2001050.01                  28.0
+0
[download]

Since the desired output appears to be CSV, one might consider using the Text::CSV_XS module for formatting the output:

use Text::CSV_XS;
my $csv = new Text::CSV_XS;

. . .
        . . .

                $csv->combine( $co_id, $company, $item, $date, $person
+, $value );
                print $csv->string, "\n";
[download]

jdporter
The 6th Rule of Perl Club is -- There is no Rule #6.