You get something like this (formatted) when querying for ticker https://api.kraken.com/0/public/Ticker?pair=XXBTZUSD

{
    "error": [],
    "result": {
        "XXBTZUSD": {
            "a": [
                "3906.00100",
                "2",
                "2.000"
            ],
            "b": [
                "3906.00000",
                "4",
                "4.000"
            ],
            ...
        }
    }
}

Third numbers (volume) in a and b are always positive whole numbers. They never contain fraction part. Given that unit of this ticker is XBT it looks absolutely unrealistic. Comparing with https://www.kraken.com/charts it also looks completely wrong. Could you please explain it?