I have the plugin set up to award integer currency, which works completely fine and as intended, except that the displayed to the player is shown using 2 decimal places, which looks really stupid when dealing with small amounts (Ex: You have received 2.00 coins)

Could you please make it so that is displayed as an integer if the integercurrency option is set true?

The integer currency setting in ecoCreature is only for the amount and not the display.

For the display, you need to refer to the documentation for the economy plugin that you have installed. It's important to note that ecoCreature delegates number formatting to the economy plugin through Vault.