The following is in FSI:
> System.Math.Round(0.2916, 2);;
val it : float = 0.29
> it * 100.;;
val it : float = 29.0
> int it;;
val it : int = 28
The result is the same everywhere I tried - a compiled F# 3.1/.NET 4.0 application, FSI in Visual Studio 2013 and 2015, .NET Fiddle, @fsibot....
Surely this is a bug somewhere, isn't it? What's going on here?
This is just how floating point numbers work. The number that appears as 29 in the output is actually slightly smaller than 29 (because floating point numbers are not precise):
> (System.Math.Round(0.2916, 2) * 100.0) - 29.0;;
val it : float = -3.552713679e-15