Does the cumulative purchase amount include consumption tax?

Whether tax is included in the "purchase amount during the aggregation period" depends on the store's "tax included price" setting at the time the order is placed.

Therefore, if you change the "tax included price" setting while an order has already been placed, the amount included in "Purchase amount during the aggregation period" will be a mix of included/excluded tax.

You can check and change by setting "tax included price" in Settings >Taxes and duties (Include sales tax in product price and shipping rate).

In Japan, it is mandatory to display the total amount for products and services for general consumers, so stores that are subject to tax will basically set it to include tax (as of September 26, 2023. Please note that changes cannot be made just to adjust the total amount in Ranky. For details, please refer to the relevant ministry page and set the appropriate setting).