Splitting files 5 at a time

Hello everyone,

  I currently have the following XSLT code.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
    <xsl:template match="/">
        <xsl:for-each select="DATA_FILE/CUSTOMER">
         <xsl:result-document
href="{FOLDER}{format-number(position(),'000000000')}.xml">
          <DATA_FILE>
              <xsl:apply-templates select="."/>
          </DATA_FILE>
         </xsl:result-document>
        </xsl:for-each>
    </xsl:template>
  <xsl:template match="@*|node()">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
  </xsl:template>
</xsl:stylesheet>

  This works perfectly and splits the XML input file per CUSTOMER. Now I
am being asked to split the XML file but instead of having 1 customer
per output file I am not being asked to split it down with 5 CUSTOMERS
per "new" output file. (And the last split must work even if there is
not a multiple of 5 CUSTOEMERS in the file).

  I have played with the for-each since I won't need a loop iteration
per CUSTOMER anymore but 1 per 5 so I tried something like

<xsl:for-each select="DATA_FILE/CUSTOMER[count() mod 5 = 0">

  But this did not work. I am certain I will have to change the
apply-templates as well but I have not even gotten to that point yet.

  Can you please let me know if I am going in the right direction here?
Any and all help is welcome.

Thank you.

P.S if you try and run the code, {FOLDER} will have to be replaced. This
is run inside of an application that calls an XSLT engine and the
{FOLDER} is replaced by the temp folder where the files are stored as
they are processed.