Помоему ваш код можно существенно сократить
echo "<center><table style='border-collapse :collapse; border-spacing :0;' border=1>\n";
echo " <tr><td width ='20'>№</td><td width='50'>Дата</td><td width='200'>Оборудование</td><td width='150'>Проделанная работа</td> <td width='80'>Сумма</td></tr>\n";
$tehas = mysql_query("SELECT *, DATE_FORMAT(data,'%d.%m.%Y') As data FROM remont_tech WHERE status = 'nomoney' WHERE user = '".intval($myrow['id'])."' ORDER BY data");
$i = 0;
$totalPrice = 0;
foreach($tehas as $tech){
echo "<tr><td>".$i++."</td><td>".$tech['data']."</td><td>".$tech['marka'].' '.$tech['model'].'('.$tech['serial'].')</td><td>'.$tech['work_id'].'</td><td>'.$tech['sum'].' Руб.</td><tr>';
$totalPrice += $tech['sum'];
}
echo"<tr><td COLSPAN=1><b>ИТОГО</b></td><td></td><td></td><td></td><td><b>".$totalPrice." Руб.</b></td></tr>";
echo "</table></center>\n";