I would:

• Use a hash of hashes, as Dhanasekar recommended
• Use split rather than a RE to extract fields
• Test for unexpected input

Something like the following...

my %transactions;

...

my @fields = split(/\s+/);

my %rec;
$rec{$_} = shift(@fields) for ( qw(date time tid status trname tramoun
+t) );

if ( $rec{status} eq "start" ) {
    $transactions{$rec{tid}} = \%rec;
} elsif ( $rec{status} eq "stop" ) {
    if ( exists($transactions{$rec{tid}}) ) {
        # report transaction time and amount
    } else {
        warn "ERROR: stop without start: $_";
    }
} else {
    warn "ERROR: unrecognized status: $_";
}
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Update: and include the date in the transaction time calculation: think about what happens if the transaction starts late one day and stops early the following day.