Configuration:
- Company Currency: MXN
- Tax 16%.
- Multicurrency, MXN and USD.
- Decimal precision: 4
- Currency Data:
MXN: rate 1.0
USD rates

| Database time | rate | Local time (Mexico) | 
| --- | --- | --- |
| 2016-09-09 00:00:01 | 0.054440 | 2016-09-08 17:00:01 |
| 2016-10-11 00:00:01 | 0.051815 | 2016-10-10 17:00:01 |

Steps to reproduce:

1. Create an invoice for 600 USD  + tax (16%) with date 09/09/16 (September 9, 2016) and when you validate in the journal entry is $12,784.7172 MXN.
3. Create a bank statement in MXN and add a line with date 11/10/16 (October 11, 2016) and amount $13,372.80 MXN.
4. When reconcile select the invoice and there is a difference ($588.0828 MXN) add a line with the difference and select an account for the difference. 
<img width="607" alt="captura de pantalla 2016-11-04 a la s 17 23 26" src="https://cloud.githubusercontent.com/assets/6758279/20025385/749605a2-a2b3-11e6-8b1a-4e9fbf1521ed.png">

**Note that the amount of difference is $588.08 in when you select the account**

5. Click on reconcile.

Expected behavior:
- Reconcile the invoice and create account move.

Current behavior:
- Raise an error  `Wrong credit or debit value in accounting entry !`

![captura de pantalla 2016-11-01 a la s 19 18 52](https://cloud.githubusercontent.com/assets/6758279/19913537/1c272866-a069-11e6-9b06-5851681c7fa5.png)

addons/account/models/account_move.py
for line in self:
            line.balance = line.debit - line.credit
    @api.model
    def _get_currency(self):
        currency = False
        context = self._context or {}
        if context.get('default_journal_id', False):
            currency = self.env['account.journal'].browse(context['default_journal_id']).currency_id
        return currency
    @api.model
    def _get_journal(self):
        """ Return journal based on the journal type """
        context = dict(self._context or {})
        journal_id = context.get('journal_id', False)
        if journal_id:
            return journal_id
        journal_type = context.get('journal_type', False)
        if journal_type:
            recs = self.env['account.journal'].search([('type', '=', journal_type)])
            if not recs:
                action = self.env.ref('account.action_account_journal_form')
                msg = _("""Cannot find any account journal of "%s" type for this company, You should create one.\n Please go to Journal Configuration""") % journal_type.replace('_', ' ').title()
                raise RedirectWarning(msg, action.id, _('Go to the configuration panel'))
            journal_id = recs[0].id
        return journal_id
    @api.depends('debit', 'credit', 'move_id.matched_percentage', 'move_id.journal_id')
    def _compute_cash_basis(self):