Yes. Generally, stores like iTunes, Amazon and others keep 30% of a sale. We get 70% of a sale (this is called the wholesale price) and share 80% of this amount to you.
Do the maths, it means you are receiving 53% of a sale, not bad, right?
For stores that offer full-track streaming, there is a proportionate share worked out differently for every store.
Therefore, monthly payouts for music streaming sales can vary each month (and are extremely challenging to calculate due to the complex rules applied by the stores!)