What percentage of sales does Gumroad take?

Can you clarify for me, when it comes to transactions on Gumroad, what exact percentage of the sales revenue does the platform retain for itself? Is this percentage standard across all sellers, or does it vary based on factors such as the type of product being sold, the seller's location, or their overall sales volume? Additionally, are there any other fees or charges that sellers should be aware of when using Gumroad for their transactions?