To check how much money you have spent on Loot Boxes, Overwatch Battle Pass, and all that kind of stuff, you have to go to your transaction history through your Battle.net account settings. However, after you see the results, you might not buy Loot Boxes and new Roadhog skins for a long time...
- Open your browser and go to Battle.net's official website
- Log in to your Battle.net account
- Click on your account name in the upper-right corner and select "Account Settings"
- Click on "Transaction History"
- You will have your entire purchase history for all games from Blizzard Entertainment that you have spent money one.
If the results look like a lot, you can also check out how to get Overwatch skins for free, so you don't harm your credit card too much. Moreover, speaking of things that are awesome and are not harming your credit card too much, be sure to check out our Overwatch hero randomizer!
Keep in mind that you won't have a specific summary of the money spent to get all the skins and loot boxes that you have in Overwatch, and you will have to count it yourself. Still, the overview is quite nice, and purchase history is quite clear to browse through.
This method works the same for Diablo III, World of Warcraft, Heroes of the Storm, Hearthstone, and pretty much every game available on the Battle.net platform. Moreover, as Overwatch is cross-platform, it will also show all the purchases that you've made on console.