pos/pos_customer_required/views/pos_config_view.xml

<?xml version="1.0"?>
<!--
    Copyright (C) 2004-Today Apertoso NV (<http://www.apertoso.be>)
    Copyright (C) 2016-Today La Louve (<http://www.lalouve.net/>)

    @author: Jos DE GRAEVE (<Jos.DeGraeve@apertoso.be>)
    @author: Sylvain LE GAL (https://twitter.com/legalsylvain)

    The licence is in the file __openerp__.py
-->

<odoo>

    <record model="ir.ui.view" id="view_pos_config_form">
        <field name="model">pos.config</field>
        <field name="inherit_id" ref="point_of_sale.view_pos_config_form" />
        <field name="arch" type="xml">
            <field name="iface_tax_included" position="after">
                    <field name="require_customer" />
            </field>
        </field>
    </record>

</odoo>