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_tax_cash_basis/tax_cash_basis.py
from openerp import models, fields, api, _
from openerp.exceptions import UserError
class AccountTaxCashBasis(models.Model):
    _inherit = 'account.tax'
    use_cash_basis = fields.Boolean('Use Cash Basis', help='Select this if the tax should use cash basis, which will \
        create an entry for this tax on a given account during reconciliation')
    cash_basis_account = fields.Many2one('account.account', string='Tax Received Account', domain=[('deprecated', '=', False)], help='Account use when \
        creating entry for tax cash basis')
class AccountMoveCashBasis(models.Model):
    _inherit = 'account.move'
    tax_cash_basis_rec_id = fields.Many2one('account.partial.reconcile', string='Tax Cash Basis Entry of', help="Technical field used to keep track of the tax cash basis reconciliation. This is needed when cancelling the source: it will post the inverse journal entry to cancel that part too.")
class AccountConfigSettings(models.TransientModel):
    _inherit = 'account.config.settings'
    tax_cash_basis_journal_id = fields.Many2one('account.journal',
        related='company_id.tax_cash_basis_journal_id',
        string="Tax Cash Basis Journal",)
class ResCompany(models.Model):
    _inherit = 'res.company'
    tax_cash_basis_journal_id = fields.Many2one('account.journal', string="Tax Cash Basis Journal")
class AccountPartialReconcileCashBasis(models.Model):
    _inherit = 'account.partial.reconcile'
    def _check_tax_exigible(self, line):