I'm more a mathematician, but I have been programming for most of my life, and I'm not afraid to dig into someone else's code.

I've recently found myself with some more time for "personal development" (don't worry, I'm still employed), so I did some more digging. I figured out how to make requests to the eBay Developer API. Here's a query for a recent example of a game whose price is interpreted incorrectly:

https://open.api.ebay.com/shopping?callname=GetSingleItem&responseencoding=JSON&siteid=0&version=1141&ItemID=233570481068&appid={YOUR_APP_ID_HERE}

You'll have to fill in your own production appID, since I don't think I should be posting mine publicly. Anyway, inside the response, we find this field:

"ConvertedBuyItNowPrice":{"Value":3.2,"CurrencyID":"USD"}

It's essentially the same if you ask for XML instead of JSON. I expect that your parsing troubles start here, perhaps by splitting at the ".", multiplying the first number by 100 and adding the second number.

After further testing, I think it's specific to prices that end in 0. Here's a way for me to reproduce it. Load the sniper tool in firefox, and open up the web console. Paste in the following javascript:

old_handler = on_channel_message;

on_channel_message = function(msg) {
  if ((90 + Number(msg["price"])) % 100 > 90 || (90 + Number(msg["shipping_cost"])) % 100 > 90) {
    console.log(JSON.stringify(msg));
  }
  old_handler(msg);
}

Wait a few minutes, and you'll start getting candidates. Here's one I found just now:

{"condition":"used","console_id":"G39","console_name":"Nintendo 3DS","estimated":1999,"item_id":"254500591537","listing_type":"bin","picture_url":"https://thumbs2.ebaystatic.com/m/mu-jobqHTAbY4BtMjeNNBCg/140.jpg","price":1803,"product_name":"Wario Ware Gold","savings":196,"shipping_cost":286,"title":"WarioWare Gold (Nintendo 3DS, 2018)","uid":"G49698","version":1005}

It says the price is 1803. However, if you go to https://www.ebay.com/itm/254500591537 , you'll see the price is actually $18.30 .