=== modified file 'account/account_move_line.py'
--- account/account_move_line.py	2011-10-24 07:25:44 +0000
+++ account/account_move_line.py	2011-11-26 10:12:15 +0000
@@ -1319,7 +1319,9 @@
                         tmp_cnt += 1
                         self.write(cr, uid,[result], {
                             'tax_code_id': tax[base_code],
-                            'tax_amount': tax[base_sign] * abs(total)
+                            'tax_amount': tax[base_sign] * abs(tax['price_unit']),
+                            'credit': tax['price_unit']<0 and -tax['price_unit'] or 0.0,
+                            'debit': tax['price_unit']>0 and tax['price_unit'] or 0.0,
                         })
                 else:
                     data = {
@@ -1332,10 +1334,10 @@
                         'ref': vals.get('ref',False),
                         'account_tax_id': False,
                         'tax_code_id': tax[base_code],
-                        'tax_amount': tax[base_sign] * abs(total),
+                        'tax_amount': tax[base_sign] * abs(tax['price_unit']),
                         'account_id': vals['account_id'],
-                        'credit': 0.0,
-                        'debit': 0.0,
+                        'credit': tax['price_unit']<0 and -tax['price_unit'] or 0.0,
+                        'debit': tax['price_unit']>0 and tax['price_unit'] or 0.0,
                     }
                     if data['tax_code_id']:
                         self.create(cr, uid, data, context)