use warnings;
use strict;
use Data::Dump qw(pp);

my %hash;
while (<DATA>) {
	chomp;
	next if /\A\s*\z/;
	my @pieces = split ',' => $_;
	for my $idx (3..4) {
		push @{
			$hash
			{$pieces[0]}
			{$pieces[1]}
			{$pieces[2]}
			[$idx-3]
		}, $pieces[$idx];
	}	
}
pp %hash;

__DATA__
Joe,A,1,85,90
Joe,A,1,80,99
Joe,A,2,50,70
Joe,A,2,60,65
Joe,A,2,87,89
Joe,B,1,82,92
Joe,B,3,30,51
Rob,A,1,64,77
Rob,B,2,20,32