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
account_id = (amount > 0 and tax_vals['account_id'] or tax_vals['refund_account_id'])
                    if not account_id: account_id = vals['account_id']
                    temp = {
                        'account_id': account_id,
                        'name': vals['name'] + ' ' + tax_vals['name'],
                        'tax_line_id': tax_vals['id'],
                        'move_id': vals['move_id'],
                        'partner_id': vals.get('partner_id'),
                        'statement_id': vals.get('statement_id'),
                        'debit': tax_vals['amount'] > 0 and tax_vals['amount'] or 0.0,
                        'credit': tax_vals['amount'] < 0 and -tax_vals['amount'] or 0.0,
                    }
                    bank = self.env["account.bank.statement"].browse(vals.get('statement_id'))
                    if bank.currency_id != bank.company_id.currency_id:
                        ctx = {}
                        if 'date' in vals:
                            ctx['date'] = vals['date']
                        temp['currency_id'] = bank.currency_id.id
                        temp['amount_currency'] = bank.company_id.currency_id.with_context(ctx).compute(tax_vals['amount'], bank.currency_id, round=True)
                    tax_lines_vals.append(temp)
        new_line = super(AccountMoveLine, self).create(vals)
        for tax_line_vals in tax_lines_vals:
            
            self.with_context(context).create(tax_line_vals)
        if self._context.get('check_move_validity', True):
            move = MoveObj.browse(vals['move_id'])
            move.with_context(context)._post_validate()
        return new_line
    @api.multi
    def unlink(self):