There's not much that I can do about this. It seems that the value 1.65 cannot be represented exactly, I see in the debugger the value 1.6499999999999999. This is smaller than 1.65 and, therefore, must round to 1.6 even without banker's rounding.
I can get the correctly rounded value when I use the datatype extended in the internal "RoundTo" procedure, but I am sure that there are cases again when this does not work. Because of the basic problem of floating point calculations, namely that floating point values theoretically are infinitely dense, but must be rounded internally due to the finite precision of 8 or 10 bytes.
I don't know what Excel and Calc are doing to get the "correct" value.