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
debit = fields.Monetary(default=0.0, currency_field='company_currency_id')
    credit = fields.Monetary(default=0.0, currency_field='company_currency_id')
    balance = fields.Monetary(compute='_store_balance', store=True, currency_field='company_currency_id', default=0.0, help="Technical field holding the debit - credit in order to open meaningful graph views from reports")
    debit_cash_basis = fields.Monetary(currency_field='company_currency_id', default=0.0, compute='_compute_cash_basis', store=True)
    credit_cash_basis = fields.Monetary(currency_field='company_currency_id', default=0.0, compute='_compute_cash_basis', store=True)
    balance_cash_basis = fields.Monetary(compute='_compute_cash_basis', store=True, currency_field='company_currency_id', default=0.0, help="Technical field holding the debit_cash_basis - credit_cash_basis in order to open meaningful graph views from reports")
    amount_currency = fields.Monetary(default=0.0, help="The amount expressed in an optional other currency if it is a multi-currency entry.")
    company_currency_id = fields.Many2one('res.currency', related='company_id.currency_id', readonly=True,
        help='Utility field to express amount currency', store=True)
    currency_id = fields.Many2one('res.currency', string='Currency', default=_get_currency,
        help="The optional other currency if it is a multi-currency entry.")
    amount_residual = fields.Monetary(compute='_amount_residual', string='Residual Amount', store=True, currency_field='company_currency_id',
        help="The residual amount on a journal item expressed in the company currency.")
    amount_residual_currency = fields.Monetary(compute='_amount_residual', string='Residual Amount in Currency', store=True,
        help="The residual amount on a journal item expressed in its currency (possibly not the company currency).")
    account_id = fields.Many2one('account.account', string='Account', required=True, index=True,
        ondelete="cascade", domain=[('deprecated', '=', False)], default=lambda self: self._context.get('account_id', False))
    move_id = fields.Many2one('account.move', string='Journal Entry', ondelete="cascade",
        help="The move of this entry line.", index=True, required=True, auto_join=True)
    narration = fields.Text(related='move_id.narration', string='Internal Note')
    ref = fields.Char(related='move_id.ref', string='Partner Reference', store=True, copy=False, index=True)
    payment_id = fields.Many2one('account.payment', string="Originator Payment", help="Payment that created this entry")
    statement_id = fields.Many2one('account.bank.statement', string='Statement',
        help="The bank statement used for bank reconciliation", index=True, copy=False)
    reconciled = fields.Boolean(compute='_amount_residual', store=True)
    matched_debit_ids = fields.One2many('account.partial.reconcile', 'credit_move_id', String='Matched Debits',
        help='Debit journal items that are matched with this journal item.')
    matched_credit_ids = fields.One2many('account.partial.reconcile', 'debit_move_id', String='Matched Credits',
        help='Credit journal items that are matched with this journal item.')
    journal_id = fields.Many2one('account.journal', related='move_id.journal_id', string='Journal',