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
@api.multi
    def action_view_invoice(self):
        invoice_ids = self.mapped('invoice_ids')
        imd = self.env['ir.model.data']
        action = imd.xmlid_to_object('account.action_invoice_tree1')
        list_view_id = imd.xmlid_to_res_id('account.invoice_tree')
        form_view_id = imd.xmlid_to_res_id('account.invoice_form')
        result = {
            'name': action.name,
            'help': action.help,
            'type': action.type,
            'views': [[list_view_id, 'tree'], [form_view_id, 'form'], [False, 'graph'], [False, 'kanban'], [False, 'calendar'], [False, 'pivot']],
            'target': action.target,
            'context': action.context,
            'res_model': action.res_model,
        }
        if len(invoice_ids) > 1:
            result['domain'] = "[('id','in',%s)]" % invoice_ids.ids
        elif len(invoice_ids) == 1:
            result['views'] = [(form_view_id, 'form')]
            result['res_id'] = invoice_ids.ids[0]
        else:
            result = {'type': 'ir.actions.act_window_close'}
        return result
    @api.multi
    def action_invoice_create(self, grouped=False, final=False):
        """
        Create the invoice associated to the SO.
        :param grouped: if True, invoices are grouped by SO id. If False, invoices are grouped by
                        (partner_invoice_id, currency)