China recently fixed their exchange rate to boost exports.?
All the transaction e.g. Telegraphic transfer or SWIFT wire transfer are processed through central bank of the country. In such kind of transaction, one country can deal with other countries to provide a fixed exchange rate. For example there was a deal between Europe and Switzerland to keep the EUR/CHF rat eat 1.2o which was revoked on January 15, 2015. But it is impossible to fix a exchange rate with all countries in the world. Also, it is impossible to maintain the fixed rate in offline transaction/cash transaction. Chine has/may have fixed the exchange rate with those countries which most of export/import business takes place with.