2.07 Why there is a gain loss amount even the Invoice & Payment rate is same?

This is due to rounding issue

Example

Currency Rate 3.80

Invoice DocAmt

IV-0001 := USD24.18 @ 3.80 := RM91.88

IV-0002 := USD19.08 @ 3.80 := RM72.50

Both Invoice Total up

USD43.26

RM164.38

Payment DocAmt

OR-0001 := USD43.26 @ 3.80 := RM164.39

Different is RM164.39 - RM164.38 := RM0.01 (Gain Loss)