Hello Cindy,
You can do the rounding in a 'Basic Match Calculation'. (There is another forum post on it here). It would be setup by retrieving the value you want to round, adding 0 and selecting a rounding option.
For commas in numbers, there isn't anything on the screens or actions that can do insertions of commas in decimals/numbers. You can do it in the actual report designer or it can be done with the SQL override in a grid.
I hope this helps,
Greg