You can't really stock based on fish size alone, you really have to go by the individual fish. Is there any paticular you are interested in? We can make recommendations on what fits best in a 10 gal, but you may want to pick some fish you like first, and then ask if they will work. Of the more common fish you can find just about anywhere, what works is pretty much guppies, platties, betta, dwarf gourami, and neon tetras. So called nano fish are an even better fit, but can be hard to find still in some shops. If you are able to order online, that will open up lots more options for you. Check out fish like boraras brigittae, microrasbora devario, dario dario, sparkling gourami, celestial pearl danios, danio erythromicron, corydoras hasbrosus, corydoras hastatus, corydoras pygmaeus, normans lampeye, hara jerdoni, yunnanilus cruciatus, pygmy sunfish, endlers livebearers, and ember tetras.