Problem with the decimal data type in Doctrine2 and Symfony3

I have an entity that has three fields of decimal type

/**
     * @var decimal
     *
     * @ORM\Column(name="cantidad", type="decimal", precision = 3, scale=2)
     */
    private $cantidad;


    /**
     * @var decimal
     *
     * @ORM\Column(name="precio_cuc", type="decimal",precision = 3, scale=2)
     */
    private $precio_cuc;


    /**
     * @var decimal
     *
     * @ORM\Column(name="precio_cup", type="decimal",precision = 3 ,scale=2)
     */
    private $precio_cup;

In my Form that the entity manages, I have it declared like this .. I only put one ..the others are equal

->add('cantidad',NumberType::class,array(
                'scale' => 2,
            ))

but at the time of saving the entity in the BD the field approaches an integer .. if I enter 4.5 it approaches it to 5.. In the BD the fields are declared as decimal too ..

What is the error that I do not see?