There are several options for "format" in the extension panel when setting up the datagrid, but how would one format a column value for currency?

I have stumbled upon the solution myself, so here it is in case someone else needs this. Just to be clear, this is a solution in classic ASP for applying US currency format to fields in the datagrid. I have not tried this in PHP...

It's actually really simple. After you've created your datagrid, you just need to make a simple modification to the file used for your datagrid in the ajax_servers folder created by the extension. Just put "FormatCurrency" in the empty quotes for the line of code in your dmx_grid file that applies to the field you want US currency formatting.

So, for example, my datagrid created the file dmx_grid3.asp in the ajax_servers folder. I can see this in the code of the page where I inserted the datagrid.

When opening dmx_grid3.asp, the first 20 lines of code or so contain all the fields used in my datagrid. One of them is for price and that's the one I want formatted for US currency. The line of code for this field looks like this:

array("Price", "", false),_

After the change for currency formatting, this line looks like this:

array("Price", "FormatCurrency", false),_

Save the file, upload to server and refresh your datagrid page in the browser and you're done!