if condition in display tag?

Use JSTL for if condition in display tag.

Include this library in your jsp page:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<display:column sortable="true" title="Grand Total">
        <c:if test="${data.zone != 'GRAND TOTAL'}">      
            <html:link action="/exceptionScoreCardGrandReport.do?zone=${data.zone}">
                <b>${data.grandTotal}</b>
            </html:link>
        </c:if>
    </display:column>