Consider the following two sentences, talking about prizes:
Two million pounds is paid out every day.
Two million pounds are paid out every day.
Both seem ok to me, actually, and I'm not sure which I'd be more likely to say. Because 'pounds' is grammatically plural, the plural agreement is fine, and because it's semantically one sum of money, the singular is also fine. But I do think there's a slight meaning difference. I think that perhaps the singular implies that there is just one prize, while the plural implies a multitude of prizes. But then perhaps I'm overthinking it.