Respuesta :

Tuniss
I think it's like this:  1          2 .         5             6
                               tens, ones, tenths, hundredths  

so rounded up it would stay the same. 
Greenleafable
No, it wouldn't be 13, because that is a tenth, not a hundredth.
As a matter of fact, 12.56 is already rounded to the nearest hundred, so you don't have to change anything - it stays the same.