In 2015, FairFX.com conducted a small study and found that rates varied by location, even within the same business. While market rates for foreign exchange are set by international trading, according to Investopedia, local businesses can offer any deal they wish for transactions.
The Washington Post notes that issues that can affect foreign exchange rates include competition from other exchange businesses, the popularity of the foreign currency requested in that area, and local speed of response to normal changes over time in the exchange rates on the global markets. Knowing the current market price helps a person exchanging money to find the deal nearest to the market rate. However, all exchange businesses and banks charge some form of markup in order to make a profit and survive.