In one particular situation I have a product 'optional items' price list. On the left of the table I have the item details and on the right the item prices with a combined total showing the cost of all the extras on the right in the last row (below all the other prices). That last figure is much larger than the individual figures and needs a wider cell to accommodate it.
The way I start the table is to use 3 columns; I then merge the middle and right cells in the last row to create a wider cell for the larger figure. Next I have to merge the left and middle cell for each row above the last to give me more space for the item details.
Ideally, the script dlawhfman is referring to and which I would also be interested in, will allow the selection of all the cells in the left and middle columns (except for the last row) and would apply a 'merge' to each row's left and middle cell separately so that we end up with just two columns – the first cell for all these rows would be wider than the first cell in the last row and vice versa for the right cells (see sample table). Currently, as far as I can see, InDesign will merge all the selected rows of cells to form one massive cell.
Sample table here (sorry, for the life of me I can't get the image to show in this post).
https://tinypic.com/r/15dublu/7