'Bounding box midpoint to grid intersection'. Once you've done that, Inkscape has very good tools for things like lining up text with objects and with other text.

Does that work for you?

Success!    In addition to the above I needed to select "Snap to Grids" (which is kinda obvious...)   I'd made a .1" grid and now I can snap objects to any grid intersection.

I really appreciate the help as is often the case with a new tool, you know what you want to do and reckon it's possible, but don't know the right way to describe it using the tool's language.

Bob