sale_discount_total/views/invoice_report.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <template id="report_invoice_document" inherit_id="account.report_invoice_document">
            <xpath expr="//table" position="replace">
              <table class="table table-condensed">
                <thead>
                    <tr>
                        <th>Description</th>
                        <th>Quantity</th>
                        <th class="text-right">Unit Price</th>
                        <!--<span t-if="o.amount_discount">-->
                            <th class="text-right" groups="sale.group_discount_per_so_line">Discount (%)</th>
                        <!--</span>-->
                        <th class="text-right">Taxes</th>
                        <th class="text-right">Amount</th>
                    </tr>
                </thead>
                <tbody class="invoice_tbody">
                    <tr t-foreach="o.invoice_line" t-as="l">
                        <td><span t-field="l.name"/></td>
                        <td>
                            <span t-field="l.quantity"/>
                            <span t-field="l.uos_id"  groups="product.group_uom"/>
                        </td>
                        <td class="text-right">
                            <span t-field="l.price_unit"/>
                        </td>
                        <!--<span t-if="o.amount_discount">-->
                            <td class="text-right" groups="sale.group_discount_per_so_line">
                                <!--<span t-field="l.discount"/>-->
                                <span t-esc="'%.2f'%(l.discount)"/>
                            </td>
                        <!--</span>-->
                        <td class="text-right">
                            <span t-esc="', '.join(map(lambda x: x.name, l.invoice_line_tax_id))"/>
                        </td>
                        <td class="text-right">
                            <span t-field="l.price_subtotal"
                                t-field-options='{"widget": "monetary", "display_currency": "o.currency_id"}'/>
                        </td>
                    </tr>
                </tbody>
              </table>
            </xpath>

            <xpath expr="//div[@class='col-xs-4 pull-right']/table/tr[2]" position="after">
                <t t-if="o.type=='out_invoice' or o.type=='out_refund'">
                    <!--<t t-if="o.discount_rate">-->
                    <tr>
                        <td>Discount</td>
                        <td class="text-right">
                            <span t-field="o.amount_discount" t-field-options='{"widget": "monetary", "display_currency": "o.currency_id"}'/>
                        </td>
                    </tr>
                    <!--</t>-->
                </t>
            </xpath>
            <!--<xpath expr="//div[@class='col-xs-4 pull-right']" position="before">-->
                <!--<t t-if="o.type=='out_invoice' or o.type=='out_refund'">-->
                    <!--<div class="col-xs-4">-->
                        <!--<t t-if="o.discount_rate">-->
                        <!--<table class="table table-condensed">-->
                            <!--<tr class="border-black">-->
                                <!--<td>Discount Type</td>-->
                                <!--<td class="text-right">-->
                                    <!--<span t-field="o.discount_type"/>-->
                                <!--</td>-->
                            <!--</tr>-->
                            <!--<tr>-->
                                <!--<td>Discount rate</td>-->
                                <!--<td class="text-right">-->
                                    <!--<span t-field="o.discount_rate"/>-->
                                <!--</td>-->
                            <!--</tr>-->
                            <!--<tr class="border-black"></tr>-->
                        <!--</table>-->
                        <!--</t>-->
                    <!--</div>-->
                <!--</t>-->
            <!--</xpath>-->
        </template>
    </data>
</openerp>