Good but Coin Buying System Is Terrible

Ok so first off great game! I decided to buy some coins with a 15$ iTunes card and first I bought 5$ worth but was ripped off! They charged me 5.02$ only 2 cents more but I couldnt buy more for 10 dollars so I bought another 5$ this time they charged like 5.30$ Im done

Theyralltakenwth about VEGA Conflict