QString("2553.278").toDouble() return 2553.2779999999997926

#include <QtCore/QCoreApplication>

#include <QDebug>

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

QString testString = QString("2553.278");

bool ok = false;
double testValue = testString.toDouble( &ok );

qDebug() << ok << QString("%1").arg( testValue, 0, 'g', 20 );
//as result we have had 'true 2553.2779999999997926' in the console

return a.exec();
}