This is good, but since (sort keys %hash) is a list, we can just take a list slice:

my %hash = ( 'b' => '2', 'a' => '1', 'c' => '3',
             'f' => '6', 'e' => '5', 'd' => '4' );

foreach my $key ( (sort keys %hash)[0..4] ) 
{
    print "$key ==> $hash{$key}\n" 
}
#prints..
#a ==> 1
#b ==> 2
#c ==> 3
#d ==> 4
#e ==> 5
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