VAT Strange Behaviour!!


I have VAT set to 17.5% and on my products it displays as this

Price: £43.40 (£50.99 inc tax)

I have tried a few VAT calculators and it should be £51 so ideally it needs to be rounded up to (£51 inc tax) to make things worse on the checkout page it does round the price up to £51.

Any ideas or help on this.

Thanks in advance