@mark.dickinson,

1) Where is your "`round` is giving the correct result in all cases"??

>>> round(4.395, 2)
4.39

2) I wrote it in my post using decimal punct:
''' Because, when the decimal string is converted to a binary floating-point number, it's 
    again replaced with a binary approximation:

    Whose exact value is 5.765 --> 5.76499999999999968025576890795491635799407958984375
                                                 &&
                         2.675 --> 2.67499999999999982236431605997495353221893310546875

    It means that, the 76(5) --> 5 replaced in a memory as 4.(999999999999)
                                                 &&
                       67(5) --> 5 replaced in a memory as 4.(999999999999) '''

3) round(2.6749999999999998, 2) --> this is the same with round(2.675, 2).

4) I also have a question for you.. Do you have any suggestion to solve this problem?