PHP unexpected result of float to int type cast

I'trying to convert a float to an int value in php:

var_dump((int)(39.3 * 100.0)); //Returns 3929 but should be 3930!
var_dump((int)(39.2 * 100.0)); //Returns 3920

I can use ceil to make it work but can somebody explain this to me?

var_dump((int)ceil(39.3 * 100.0)); //Returns 3930