The sales ranking on the Amazon book product page is based on some of the popular categories and/or keywords associated with a given book. This shows how that book is selling compared with other books in the same category or subcategories. For more information, you can click here.
It should also be noted that the sales ranking does not correspond to any guaranteed level of sales, as this ranking is completely dependent on how many copies of the other books in the same categories are being sold -- data that is not made available by Amazon.
In other words, Amazon chooses subcategories and categories related to the categories (aka 'BISAC codes') and keywords that the author selected, based on sales. The sales ranking categories will not necessarily always be exactly the same as the categories the author selected and may vary from one country to another. Tellwell unfortunately does not have full control over what categories show up under the sales rankings, however, we can change the categories and keywords associated with the book upon request (your Managed Distribution Fee covers one such change annually).
If you have any concerns with the categories showing up on your book's Amazon product page, please reach out to firstname.lastname@example.org