While GameSparks does not support floating point currencies out of the box, it is possible. Below are two examples of how this could be achieved within GameSparks.

• You could round your currency up. For example: If an item costs 2.5 coins and your player had 5 coins, treat them as 250 and 500 coins respectfully and then handle the decimal points when displaying them to your players. 
• If players are rewarded with coins for a set number of actions / achievements / over time, treat these as a second currency, once that reaches 100, credit your player one coin and then remove the number of actions (or other measurement) from the second currency.