First off, I'm not sure what order you expect your output to be. I'm going to guess that you want something like this:

.4  .6  .1
.3  .5  .1
.0  .2  .1
.5  .7  .1
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In which case, I would create an array with the order of keys you want to go through:

my @keys = qw(start stop step);
for my $type (@keys) {
  print $point->{$type}, "\t";
}
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If some of the keys may not appear, you could skip them:

my @keys = qw(start stop step);
for my $type (@keys) {
  next unless exists $point->{$type};
  print $point->{$type}, "\t";
}
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Or, in the spirit of TMTOWTDI, you could have a hash of weightings:

my %weights = ( start => 10, stop => 20, step => 30 );
for my $type ( sort { $weights{$a} <=> $weights{$b} } keys %$point ) {
  print $point->{$type}, "\t";
}
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But I like the array better. No actual sorting required. The hash weights are more useful when you have great numbers of possible keys to sort, but only a few keys will be in any given hash. In this case, you may not want to generate the weights by hand, but generate them in code:

my %weights = do { my $i = 0; map { $_ => $i++ } qw(start stop step ot
+her stuff in order here) };
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Hope that helps.