The Chinese Yuan will be, if not already, in such a position. With enough reserves to match the currency you have in circulation, you dictate how much your currency is worth.
Yes, in view of its foreign reserves the Yuan has considerable leverage but it can't get into a band as any large scale move will result in other major currencies reacting quickly. It will be difficult to control it within a band. Its something that the Chinese has been trying to put their arms around as appreciation at that rate is not going to help anyone.
SGD is a nobody in the world of forex except that Singapore is major forex hub. It can dive, jump, go sideways and nothing will happen except for Singaporeans. The rich indon, Thais, Malaysians and other foreigners have acu accounts in Singapore denominated in the strong currencies such as USD, Euro etc.