pos/pos_ticket_logo/static/src/xml/pos.xml

<?xml version="1.0" encoding="UTF-8"?>

<templates id="template" xml:space="preserve">

    <t t-extend="PosTicket">
        <t t-jquery="div[class='pos-sale-ticket']" t-operation="prepend">
            <div class="pos-center-align">
                <img t-att-src="widget.pos.company_logo_base64"/><br />
            </div>
        </t>
    </t>

</templates>