sub round {
  my $n = shift;
  my $abs  = abs( $n );
  return 0 if $abs < 0.5;
  my $sign = $n/$abs;
  return int( $abs + 0.5 ) * ( $n/$abs );
}
print round( $_ ), $/ for qw( -1.5 -0.5 0 0.5 1.5 );
__END__
-2
-1
0
1
2