I was just re-reading What’s New In Python 3.0 and it states:

The round() function rounding strategy and return type have changed.

Exact halfway cases are now rounded to the nearest even result instead

of away from zero. (For example, round(2.5) now returns 2 rather than

3.)

and

the documentation for round:

For the built-in types supporting round(), values are rounded to the

closest multiple of 10 to the power minus n; if two multiples are

equally close, rounding is done toward the even choice

So, under **v2.7.3**:

```
In [85]: round(2.5)
Out[85]: 3.0
In [86]: round(3.5)
Out[86]: 4.0
```

as I’d have expected. However, now under **v3.2.3**:

```
In [32]: round(2.5)
Out[32]: 2
In [33]: round(3.5)
Out[33]: 4
```

This seems counter-intuitive and contrary to what I understand about

rounding (and bound to trip up people). English isn’t my native language but

until I read this I thought I knew what rounding meant :-/ I am sure

at the time v3 was introduced there must have been some discussion of

this, but I was unable to find a good reason in my search.

- Does anyone have insight into why this was changed to this?
- Are there any other mainstream programming languages (e.g.,
*C, C++, Java, Perl,*..) that do this sort of (to me inconsistent) rounding?

What am I missing here?

UPDATE: @Li-aungYip’s comment re “Banker’s rounding” gave me the right search term/keywords to search for and I found this SO question: Why does .NET use banker’s rounding as default?, so I will be reading that carefully.