sort can take a block which dictates the sort criteria. Consider:

use strict;
use warnings;
use Text::xSV;

my $data = <<'END_DATA';
02/28/2009|02062672169||4.99|9801|1.0|
02/28/2009|78513836100||4.96|9639|1.0|
02/28/2009|71171973992||19.99|9749|1.0|
02/28/2009|01463314931||19.99|9802|1.0|
END_DATA

open my $inFile, '<', \$data or die "Failed to open data file: $!";

my $csv = Text::xSV->new (fh => $inFile, sep => '|');
my @rows;

push @rows, $_ while $_ = $csv->get_row;
@rows = sort {$a->[1] <=> $b->[1]} @rows;
print join "\n", map {join '|', map {$_ || ''} @$_} @rows;
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Prints:

02/28/2009|01463314931||19.99|9802|1.0|
02/28/2009|02062672169||4.99|9801|1.0|
02/28/2009|71171973992||19.99|9749|1.0|
02/28/2009|78513836100||4.96|9639|1.0|
[download]