Could be done via both Hash of Hashes as well as Hash of Arrays

See if this works....

Input File

team_1, location_2, tool_1, 4
team_3, location_1, tool_3, 3
team_2, location_3, tool_3, 2
team_2, location_4, tool_2, 5
team_3, location_2, tool_5, 3
team_1, location_1, tool_3, 1
team_2, location_4, tool_5, 6
team_4, location_2, tool_5, 3
team_5, location_4, tool_4, 2
team_2, location_4, tool_5, 3
team_3, location_3, tool_4, 4
team_2, location_4, tool_5, 3
team_4, location_1, tool_1, 1
team_1, location_3, tool_5, 3
team_3, location_2, tool_5, 5
[download]

Code

use v5.14;
use Data::Dumper;
my %locHash;

foreach(`cat dataFile`){
    my ($locName, $toolName, $toolNum)=(split(/\,/,))[1..3];
    $locHash{$locName}->{$toolName}=$toolNum;
}

print "Data::Dumper:\n";
print Dumper(\%locHash);

say "<ToolLocations>";
foreach my $locName(sort keys %locHash){
    say "   <ToolLocation>";
    say "       <LocationName>",chomp($locName),"</LocationName>";
    say "       <ToolList>";
    foreach my $toolDetail(sort keys %{$locHash{$locName}}){
        say "       <Tool>";
        say "           <ToolName>",chomp($toolDetail),"</ToolName>";
        say "           <ToolNum>",chomp($locHash{$locName}->{$toolDet
+ail}),"</ToolNum>";
        say "       </Tool";
    }
    say "       </ToolList>";
    say "   </ToolLocation>";
}
say "</ToolLocations>";
[download]

Output

Data::Dumper:
$VAR1 = {
          ' location_1' => {
                             ' tool_3' => ' 1
',
                             ' tool_1' => ' 1
'
                           },
          ' location_3' => {
                             ' tool_5' => ' 3
',
                             ' tool_3' => ' 2
',
                             ' tool_4' => ' 4
'
                           },
          ' location_4' => {
                             ' tool_5' => ' 3
',
                             ' tool_2' => ' 5
',
                             ' tool_4' => ' 2
'
                           },
          ' location_2' => {
                             ' tool_5' => ' 5
',
                             ' tool_1' => ' 4
'
                           }
        };
<ToolLocations>
   <ToolLocation>
       <LocationName>0</LocationName>
       <ToolList>
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       </ToolList>
   </ToolLocation>
   <ToolLocation>
       <LocationName>0</LocationName>
       <ToolList>
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       </ToolList>
   </ToolLocation>
   <ToolLocation>
       <LocationName>0</LocationName>
       <ToolList>
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       </ToolList>
   </ToolLocation>
   <ToolLocation>
       <LocationName>0</LocationName>
       <ToolList>
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       <Tool>
           <ToolName>0</ToolName>
           <ToolNum>1</ToolNum>
       </Tool
       </ToolList>
   </ToolLocation>
</ToolLocations>
[download]