use strict;
use warnings;

...

my $sql = qq|
    SELECT ID, tutorID, Latitude, Longitude, City, State, Zipcode
      FROM $table_tzips
     WHERE Zipcode IS not NULL
|;

my $sth = $dbh->prepare($sql);

my %closest;
$sth->execute();
while (my $tzips = $sth->fetchrow_hashref()) {
    my $tutorID = $tzips->{tutorID};
    my $dist = calculate_distance(
        $clong, $clat,
        $tzips->{Longitude}, $tzips->{Latitude} );

    next
        if $closest{$tutorID}
        && $closest{$tutorID}{dist} <= $dist;

    $closest{$tutorID} = {
        ID      => $tutorID,
        tzipID  => $tzips->{ID},
        Dist    => $dist,
        City    => $tzips->{City},
        State   => $tzips->{State},
        Zipcode => $tzips->{Zipcode},
    };
}

my @report_fields = qw( tzipID ID Dist City State Zipcode );

for my $tutor ( sort{ $a->{dist} <=> $b{dist} } values(%closest) ) {
    print(join(', ', @{$tutor}{@report_fields}), "\n");
}