In your "foreach" loops, you're traversing a list of keys within the hashes and getting back just the value of those keys. Not a reference you can use directly to access the hash. To turn this into such a reference you can do like so:

my $inner = $ret->{$room};
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That is, you lookup the value held in the outer hash, using the key that you're currently looping over. A complete program might look like this:

use strict;
use warnings;
use feature 'say';
my $ret = {     room1 => { tag => 5,  status => 'lazy',   id => 5823 }
+,
                room2 => { tag => 10, status => 'active', id => 1234 }
+,
};

for my $room ( sort keys $ret ) {
        say $room;
        my $inner = $ret->{$room};
        say "\t$_ => $inner->{$_}" for sort keys $inner;
}
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I was surprised to see that you could get "keys" for a scalar.

Then I RTFM, and found:

Starting with Perl 5.14, "keys" can take a scalar EXPR, which must contain a reference to an unblessed hash or array. The argument will be dereferenced automatically. This aspect of "keys" is considered highly experimental. The exact behaviour may change in a future version of Perl.

So - I would continue to code your last line as:

say "\t$_ => $inner->{$_}" for sort keys %$inner;
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Which, to me, is safer and saner.

             "I'm fairly sure if they took porn off the Internet, there'd only be one website left, and it'd be called 'Bring Back the Porn!'"
        -- Dr. Cox, Scrubs

Or simply do like so:

use warnings;
use strict;
use feature 'say';

my $ret = {
    room1 => { tag => 5,  status => 'lazy',   id => 5823 },
    room2 => { tag => 10, status => 'active', id => 1234 },
};

for my $room ( sort keys $ret ) {
    say $room, ' : ', join "\t" => %{ $ret->{$room} };
}
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