I prefer this:

my %total;
while ( my $data = $t_sth->fetchrow_arrayref ) {
    my ( $amt, $id ) = @$data;
    $total{$id} += $amt / PRECISION;
}

$tcash        += delete $total{$CASH}        || 0;
$taccount     += delete $total{$ACCOUNT}     || 0;
$tcheck       += delete $total{$CHECK}       || 0;
$tgift        += delete $total{$GIFT}        || 0;
$tvoucher     += delete $total{$VOUCHER}     || 0;
$tcc_man_auth += delete $total{$CC_MAN_AUTH} || 0;

$tcredit += $_ foreach values %total;
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Slightly longer, but much more straightforward. (Although I did need the || 0 bits to make it quiet under warnings.) And, of course, all of the variables following a naming pattern suggests that you would be better off using a hash...

BTW I hope you learned that using short-circuting conditionals as a control structure is a bad idea.