You can define pricing rules for your exports to Spartoo.com, these rules apply to prices including all taxes.
You can define a pricing rule for each profile.
Pricing rules are ranges, for each range you can set a value or a percentage.
Here is an example:
In this example, all the prices of your products between 0 and 100 euros will be increased by 5% and then from 101 to 500 by 3%, and for 501 euros and more by 1%.
In case of malfunction or doubt on the operation, unselect all categories and keep just one to minimize the number of offers exported, it will be easier for you to isolate the source of the error.