Reading the DotStar datasheet - power requirements
You have correctly worked out:

I(A) = P(W) / V(V)

I = 0.2 / 5
I = 0.04A

MAX:
I = 1 / 5
I = 0.2A


From that it seems it will use between 40 - 200mA depending on brightness.

Sink current refers to the current required to drive the led's digital input from your MCU's digital output.



More information on current sinking