All the PV values of each groupID is then added and the sum is formatted till six decimal values. Here's the XSLT file:

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method = "text"  omit-xml-declaration="no" standalone="no"
indent="yes"  />
	<xsl:key name = "keyGroupID"  match ="RiskRow" use = "GroupID" />
	<xsl:template match="/">
		<xsl:for-each select =
"//RiskRow[generate-id(.)=generate-id(key('keyGroupID',GroupID)[1])]">
			<xsl:variable name="lngGroupID"><xsl:value-of
select="GroupID"/></xsl:variable>
			<xsl:text>The groupID is =</xsl:text>
			<xsl:value-of select="$lngGroupID" />
			<xsl:text>|</xsl:text>
			<xsl:variable name="1stTradeID"
select="//RiskRow[GroupID=$lngGroupID]"/>
			<xsl:call-template name="ShowEmployeesInTeam">
				<xsl:with-param name="1stTradeID" select="$1stTradeID" />
			</xsl:call-template>
			<!--Put carriage return and linefeed character -->
			<xsl:text>

</xsl:text>
		</xsl:for-each>
	</xsl:template>

	<xsl:template name="ShowEmployeesInTeam">
		<xsl:param name="1stTradeID"/>
		<!--Show the details of Employee currently being processes -->
		<xsl:for-each select="$1stTradeID">
			<!--Include the columns here-->
			<xsl:value-of select="TradeID" /> <xsl:text> </xsl:text>
			<xsl:value-of select="PVinEuro1" /><xsl:text>|</xsl:text>
		</xsl:for-each>
		<xsl:text>Sum is = </xsl:text>
		<!--Summation on PVinEuro1 and format the number till 6 decimal point-->
		<xsl:value-of
select='format-number(sum($1stTradeID/PVinEuro1),"###############.######")
' />
	</xsl:template>
</xsl:stylesheet>

<?xml version="1.0"?>
<MarketConformity>
<RiskRow><GroupID>244133L</GroupID><TradeID>244133L_EUR_STUB</TradeID><PVi
nEuro1>-11121619.203</PVinEuro1></RiskRow>
<RiskRow><GroupID>325866L</GroupID><TradeID>325866L_EUR_STUB</TradeID><PVi
nEuro1>-12121619.2938</PVinEuro1></RiskRow>
<RiskRow><GroupID>325867L</GroupID><TradeID>325867L_EUR_STUB</TradeID><PVi
nEuro1>-14121619.293864</PVinEuro1></RiskRow>
<RiskRow><GroupID>502722L</GroupID><TradeID>502722L_EUR_STUB</TradeID><PVi
nEuro1>-13121543.293643</PVinEuro1></RiskRow>
<RiskRow><GroupID>502722L</GroupID><TradeID>502722L_PLN_STUB</TradeID><PVi
nEuro1>-11234329.698236</PVinEuro1></RiskRow>
<RiskRow><GroupID>325866L</GroupID><TradeID>506593L_EUR_STUB</TradeID><PVi
nEuro1>-11134543.12963</PVinEuro1></RiskRow>
<RiskRow><GroupID>244133L</GroupID><TradeID>542056L_EUR_STUB</TradeID><PVi
nEuro1>-12342342.769823</PVinEuro1></RiskRow>
<RiskRow><GroupID>325867L</GroupID><TradeID>553257L_PLN_STUB</TradeID><PVi
nEuro1>-98745908.128361</PVinEuro1></RiskRow>
<RiskRow><GroupID>570079L</GroupID><TradeID>570079L</TradeID><PVinEuro1>-6
4325623.693286</PVinEuro1></RiskRow>
<RiskRow><GroupID>570079L</GroupID><TradeID>570084L_EUR_STUB</TradeID><PVi
nEuro1>-67824233.986723</PVinEuro1></RiskRow>
<RiskRow><GroupID>244133L</GroupID><TradeID>570090L</TradeID><PVinEuro1>-5
6721463.972345</PVinEuro1></RiskRow>
<RiskRow><GroupID>325866L</GroupID><TradeID>570096L</TradeID><PVinEuro1>-8
7623763.23442</PVinEuro1></RiskRow>
<RiskRow><GroupID>325867L</GroupID><TradeID>570098L</TradeID><PVinEuro1>-7
9843267.4232</PVinEuro1></RiskRow>
<RiskRow><GroupID>244133L</GroupID><TradeID>570099L</TradeID><PVinEuro1>-8
7246234.23423</PVinEuro1></RiskRow>
<RiskRow><GroupID>325866L</GroupID><TradeID>570106L</TradeID><PVinEuro1>-3
2423896.4732</PVinEuro1></RiskRow>
</MarketConformity>