Unexpected behavior casting a DECIMAL to an INT in PHP Version 7.0.33

Question

In the example below, you will some examples where the INT that is expected is different than what is actually shown via PHP Version 7.0.33

Below is the PHP code with the expected vs unexpected results.

Any idea why some results are incorrect?

  echo (int) (129.34 * 100) . '<br/>';
  // WORKS: Result: 12934
  
  echo (int) (129.66 * 100) . '<br/>';
  // WORKS: Result: 12966
  
  echo (int) (129.67 * 100) . '<br/>';
  // WRONG!: Result: 12966
  // Should be: 12967
  
  echo (int) (129.68 * 100) . '<br/>';
  // WORKS: Result: 12968
  
  echo (int) (129.69 * 100) . '<br/>';
  // WORKS: Result: 12969
  
  
  echo (int) (259.34 * 100) . '<br/>';
  // Doesn't work! Shows 25933, should be 25934
  
  echo (int) (226.66 * 100) . '<br/>';
  // WORKS: Result: 22666
  
  
  // All work
  echo (int) (25.92 * 100) . '<br/>';
  echo (int) (25.93 * 100) . '<br/>';
  echo (int) (25.94 * 100) . '<br/>';
  
  // All work!
  echo (int) (229.65 * 100) . '<br/>';
  echo (int) (226.66 * 100) . '<br/>';
  echo (int) (229.67 * 100) . '<br/>';
  echo (int) (229.68 * 100) . '<br/>';
  echo (int) (229.69 * 100) . '<br/>';