sizing grids to amount of data up to a maximum size

Is there a way to programatically have all of our grids be sized based on the amount of data up to a maximum? We are using grids throughout our website and trying to find a way to have them all behave the same way (in both IE and FireFox), being that if there is just 10 rows in the grid, then have the grid be sized without scrollbars to fit those 10 rows...but if the grid has 100 rows, then have the grid sized (to some arbitrary row number/size) and allow scrolling.

I did see one post about counting rows and multiplying by a size in order to achieve this, but I don't think that it'll work for grids that have to show in both IE and FireFox (as the row heights seem to be different between the two).

If anyone has any ideas, that would be great?
Thanks