The royalty rate per streams for almost all of the interactive streaming services is about 10.5% of their monthly gross revenue divided by the number of streams divided by two.
For example, if a service had $1,000 in Gross Revenue in one month and there were 750,000 streams The per stream mechanical royalty would be:
1,000/750,000 = $0.00133333
$0.00133333/ 2 = $0.00066666
The per stream mechanical royalty rate in this example is $0.00066666 per streams
You can see the Spotify monthly mechanical royalty per stream rates here