Nice, this makes the grouping option much more useful. For completeness you could add 0.0025, and possibly 0.0005, 0.00025, 0.0001, and 0.00005 if you think they might be useful.
I think this will ultimately be user-customizable and order-of-magnitude dependent. For instance, if the price of Bitcoin is $10k, you probably don't want to group the order book down to 0.0001, which is 8 orders of magnitude smaller than the price. As it stands, 0.0001 is useful when the price is ~$3, which is ~4.5 orders of magnitude.