You should, as good practice, use strict; and use warnings;, along with explicit initializing variables - it's obviously not necessary but can save headaches. There are a number of so-called best practices you aren't following, but they are less essential (4-space indent, clear names for variables, ...). Is there a reason you hold off on parsing your @temp array 'till you've read in an entire block? From what I read, it seems like you could do the same thing with:

use strict;
use warnings;

my $transaction_flag = 0;
my $match_flag = 0;
my $count = 0;

my @value_list = ('154216722');
my @transaction = ();

while (my $line = <>) {
    if ($line =~ /\<BEGIN Transaction\>/){
        $transaction_flag = 1;
    }

    if ($transaction_flag) {
        push @transaction, $line;
        for (@value_list) {
            if ($line =~ /$_/) {
                $match_flag = 1;
                $count++;
            }
        }
    }

    if ($line =~ /\<\/END Transaction\>/){
        $transaction_flag = 0;
        if ($match_flag) {
            print @transaction;
        }
        $match_flag = 0;
        @transaction = ();
    }
}
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This also compares against an entire list of match values at once, which is likely desirable if you want to test against 5000 numbers.