The total price of an in-game purchase is indicated in your billing statement prior to finalizing the payment. In some cases, the total cost includes the applicable taxes, depending on your country/region.
 
All in-game purchases are processed by the app store from which you have downloaded the game (Google Play/App Store/Huawei AppGallery/Amazon Appstore/Microsoft Store/Samsung Galaxy Store). You can find the full receipt including tax in the purchase history section of your Google/Apple/Huawei/Amazon/Microsoft/Samsung Galaxy account. For further instructions, please refer to this article.
 
NOTE: when payments are made through the App Store, multiple purchases might be grouped into a single charge, so you might not get a separate email receipt for each purchase.
Sometimes, the charges may appear in your purchase history a few days after the purchases were made.  If you are not sure what purchases are reflected in the receipts, please review your payment status in the purchase history section of your Apple account. More information regarding the iOS billing specifics can be found here.