Simple conditional output by xsl:if
<rohlik cena="5"> ... </rohlik>
Template adding content if price > 2:
<xsl:template match="rohlik">
<p>
<xsl:if test="cena>2">
<span class="expensive">Drahý</span>
</xsl:if> rohlík - cena <xsl:value-of select="@cena"/> Kč </p>
</xsl:template>