Most countries that have the same system don't change prices, they just go on as they always have done as the change only affects people paying with cash.
If you pay by card then you pay the exact amount of your transaction, as you currently do - if your total is £9.02 then you pay £9.02; if it's £9.44 then you pay £9.44
However, if you pay with cash then they just automatically round to the nearest 5p, sometimes you will pay a couple of pence "extra" other times it will be a couple of pence cheaper so they ultimately balance out - if your total is £9.02 then you pay £9; if your total is £9.44 then you pay £9.45.