A 'Penny Share' is a loose phase always describe shares with a speculative appeal because of their low value.
Indeed there is not a formal rule to define when a stock turns into a Dime Share and also different observers can use different criteria.
Most brokers could stipulate which a cent share need a value below some top limit - that are anything from 50p as much as £3. Other people may indicate a roof on top of the Marketplace Capitalisation of the business.