sub get_fuzzy {
    my ($k, $h) = @_;
    return $h->{$k} if exists $h->{$k};

    for (sort keys %$h) {
        return $h->{$_} if $_ gt $k;  # if keys are numeric, change "gt" to ">"
    }

    return undef;    # if key is higher than the highest
}

my %hash = (a=>1, c=>3, e=>5, g=>7, i=>9);
print "|", join('|', map { get_fuzzy($_, \%h) } a..j), "|\n";