Where would you like to do this, do you want to show this on a page as text, in a grid or do you want to have this in your database?
I think it is at least worth to take a look at this:
As my understanding you have a Decimal value of 12.3333
By this Decima value you need only 12.33
For this use this parseDecimal(toString($Decimal),'#.##')
It will return 12.33 as Decimal value