Try this

        <record id="product_template_form_view_inherit_inherit"    model="ir.ui.view">
            <field name="name">product.template.form.inherit</field>
            <field name="model">product.template</field>
            <field name="inherit_id" ref="product.product_template_form_view" />
            <field name="groups_id" eval="[(6, 0, [ref('point_of_sale.group_pos_user') ])]"/>
            <field name="arch" type="xml">
                <xpath expr="//page[@string='Procurements']" position="attributes">
                         <attribute name="invisible">True</attribute>
                </xpath>
            </field>
        </record>

Note: (6, 0, ids) - replaces old groups and adds POS user group.  This is usually done when manipulating List values.

For more info check odoo 8 documentation.(https://www.odoo.com/documentation/8.0/reference/orm.html#model-reference) --Check at WRITE(vals)