QFont::setPointSizeF() doesn't scale smoothly

#include <QtGui>

class MyWidget : public QWidget
{
public:
    MyWidget() : QWidget(0)
    {
    }

protected:
    virtual void paintEvent(QPaintEvent *e)
    {
        QPainter p(this);
        p.scale(10, 10);
        for (int i = 0; i < 10; ++i) {
            QFont font("Times");
            font.setPointSizeF(0.2 * (i + 1));
            p.setFont(font);
            p.drawText(1, 2 + 3 * i, QString("This should be point size %1!").arg(font.pointSizeF()));
        }
    }
};

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    MyWidget widget;
    widget.resize(400, 300);
    widget.show();
    return app.exec();
}