Repairshopr has support for multiple levels of categories.
To edit these, go to Admin > Inventory Preferences. Here you can enable these with the Show Categories option.
This will then give you a category tree you can customize:
In addition, you can enable tabs at the top of your Inventory page to make organizing and sorting inventory easier.
The suite also lets you organize your POS with category drill-downs. To enable this, go to Admin > POS Preferences:
Your POS inventory will now show with high-level categories: