Impacted versions:

[9.0]
Tested in runbot http://174550-9-0-10dcec.runbot10.odoo.com/

Steps to reproduce:

Set the Tax Calculation Rounding Method to "Round Globally" 
Create a Sales Order with the following lines with 7% taxes

1) 5,095.20 
2) 523.20 
3) 80.64 
4) 54.12 
5) 182.00 
6) 186.20 
![image](https://cloud.githubusercontent.com/assets/16055718/19144073/309aa082-8bda-11e6-81d0-2461c4e9a467.png)

Create a Sales Invoice with the same lines with 7% taxes
![image](https://cloud.githubusercontent.com/assets/16055718/19144078/38048b58-8bda-11e6-9c2b-4b501cfa1e12.png)

Current behavior:

The total taxes in Sales Order are $477.48 

The total taxes in Sales Invoice are $477.50 

Expected behavior:

Both the total taxes in Sales Order and Sales Invoice should be 477.50 

Video/Screenshot link (optional):

addons/sale/sale.py
"""
        Prepare the dict of values to create the new invoice line for a sales order line.
        :param qty: float quantity to invoice
        """
        self.ensure_one()
        res = {}
        account = self.product_id.property_account_income_id or self.product_id.categ_id.property_account_income_categ_id
        if not account:
            raise UserError(_('Please define income account for this product: "%s" (id:%d) - or for its category: "%s".') % \
                            (self.product_id.name, self.product_id.id, self.product_id.categ_id.name))
        fpos = self.order_id.fiscal_position_id or self.order_id.partner_id.property_account_position_id
        if fpos:
            account = fpos.map_account(account)
        res = {
            'name': self.name,
            'sequence': self.sequence,
            'origin': self.order_id.name,
            'account_id': account.id,
            'price_unit': self.price_unit,
            'quantity': qty,
            'discount': self.discount,
            'uom_id': self.product_uom.id,
            'product_id': self.product_id.id or False,
            'invoice_line_tax_ids': [(6, 0, self.tax_id.ids)],
            'account_analytic_id': self.order_id.project_id.id,
        }
        return res
    @api.multi
    def invoice_line_create(self, invoice_id, qty):