You can use a step down ring (72mm-67mm) with a 72mm close-up lens.
However, you should consider investing in extension tubes instead. They are generally cheaper and without IQ degradation.
For magnification factors and focus distance, check this link out:
I use extension tubes with prime lenses but prefer close up lenses with zoom lenses because with extension tubes your focus changes with zooming. So, if you're really close, whenever you zoom a bit you've got to move your setup to refocus.
Great point Thanx, I think I'll go wit Hoya at this point, any thoughts?
The step up ring from 67 to 72 would be a good option so you could use the 500D. But as long as a third party option is a 2 element, coated lens it probably will perform well. I'm not familiar with all the options as I use the 500D.
I don't know anything about how well they work but besises using a step up ring there are choices available.