hello,
the solution to this problem is in file:
/includes/modules/payment/paypal_standard.php
line 643 from:
return number_format(tep_round($number * $currency_value, $currencies->currencies[$currency_code]['decimal_places']), $currencies->currencies[$currency_code]['decimal_places'], '.', '');
to:
return number_format($number * $currency_value, $currencies->currencies[$currency_code]['decimal_places'], '.', '');
regards,
Emmanuel