use warnings;
use strict;

my $str = '1START   ACCOUNTA     XXXXXMA      12345     XYZ111          1START   ACCOUNTB     XXXXXBR      12345     XYZ191          1START   ACCOUNTA     XXXXXNY      54321     XYZ131';
my $i = 0;
while ($str =~ /(\S+)/g) {
    print "$1 ";
    $i++;
    print "\n" if $i % 5 == 0;
}

__END__

1START ACCOUNTA XXXXXMA 12345 XYZ111 
1START ACCOUNTB XXXXXBR 12345 XYZ191 
1START ACCOUNTA XXXXXNY 54321 XYZ131