Introduction to Stamp Duty on shares and Stamp Duty Reserve Tax (SDRT): Stamp duty rates: Stamp Duty - rounding up
FA99/S112 (1) (b) requires that Stamp Duty is “rounded up (if necessary) to the nearest multiple of £5”. This means that unless the figure arrived at by applying the Stamp Duty rate is an exact multiple of £5 it is rounded up.
For example, a consideration of £2000 dutiable at a rate of 0.5% attracts duty of exactly £10. Consideration of £2001 attracts duty of £10.005 which is rounded up to £15. The fact that .005 of a pound does not exist in coinage does not mean that it is ignored. To do so would be to round down, for which there is no statutory authority.
This rounding up provision applies irrespective of the rate of duty that is applied.