Problem at the Bank

A bank customer had £100 in his account. He then made 6 withdrawals, totaling £100. He kept a record of these withdrawals, and the balance remaining in the account, as follows:

Withdrawals	Balance left
£50	£50
£25	£25
£10	£15
£8	£7
£5	£2
£2	£0

£100	£99

Why are the Totals not exactly right?

Puzzle supplied by Richard Rider

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