El else if está aninado con el primer if, su corchete es el último, por lo tanto siempre te retornará 0.
Prueba así
Código PHP:
Ver originalif($sin_impresion == 1){
if($tintas == 1){
$sin_impresion = ($sin_impresion * 1.05);
}elseif ($tintas == 2){
$sin_impresion = ($sin_impresion * 1.10);
}elseif ($tintas == 3){
$sin_impresion = ($sin_impresion * 1.15);
}elseif ($tintas == 4){
$sin_impresion = ($sin_impresion * 1.2);
}elseif ($tintas == 5){
$sin_impresion = ($sin_impresion * 1.25);
}elseif ($tintas == 6){
$sin_impresion = ($sin_impresion * 1.3);
}elseif ($tintas == 7){
$sin_impresion = ($sin_impresion * 1.35);
}
}
else if ($sin_impresion == 0){
if($barniz == 1){
$sin_impresion = ($sin_impresion * 1.4);
}else{
$barniz = 0;
}
}