Well, it depends on the device used and whether you left it on just for the music.

Let's say you left a Macbook Air (2011) on playing the album. It has a 50 watt-hour battery, which lasts 7 hours, so it uses ~0.12 watt-hour/minute. Since the album has ten tracks of around 30s, that's 5 minutes * 0.12 Wh/m, so ~0.6 watt-hour in total.

The average price of residential electricity in the US is 11.72c/kWh (Dec. 2013), so that ends up at around $0.00007/album.

Since he says he gets $0.005/listen, or $0.025/album, that's still significantly profitable.

If you're one of those people who leaves the smartphone on anyway, the cost would probably be negligible.

Of course, it probably wouldn't matter anyway since the fixed transaction costs would make it unreasonable to send so small donations.