BUG #8317: ROUND(double*1/2) != ROUND(1/2*double)

The following bug has been logged on the website:

Bug reference: 8317
Logged by: Rémi
Email address: remi(dot)cura(at)gmail(dot)com
PostgreSQL version: 9.2.4
Operating system: Ubuntu 12.0.4 32 bits hosted by a VirtualBox
Description:

Hello;
I ran into a strange behaviour.
Initially it showed in a group by, but is also happens in regular select :

example :
SELECT 2*ROUND(1/2*3.2)
--> gives 0
SELECT 2*ROUND(3.2*1/2)
--> gives 3

Obviously both should return the same thing, preferably 3.
It looks like a bug to me, or at least a non desirable behaviour.

Cheers,
Rémi