I am having a bit of trouble with a selling price field and its associated (extenedSell - field which is a formula field 

in my image below I can iner my cost price then either key in the sell price (which stores that exact amount) and then goes back to calculate the markup field value (this works as expected - 100%)

 ie I have key in £9.41 (and this exact value has been stored)

OR i can calculate the markup field (mkup) and this will then go onto calculate the sell price - then work 95% time until you hit a value that is greater then 2 decimal points

as you can the rue price is £9.405 but Ninox will display £9.41 

on the quote grid as you can sell the extended sell the formula field (ext Sell) returns the actual stored value

whereas I want it to be £18.82

this only accurs when there is a rounding issue

 I have tried many combinations of setting round seeting on both the sell price and on the formula but nothing doing - because all these do is set a display (what you see) as opposed that what is store. Thus what I need to do is calculate from the margin  - but instead of storing a 3 decimal place - I nned to store the valus as if I had keyed it in as a rounded figure (ie 2 decimal places)

I did find this RoSoft_Steven set about 5 years ago and tried to use this in my Mkup trigger 

 if 'Cost Price' > 0 then
    'Sell Price' := 'Cost Price' * Mkup / 100 + 'Cost Price';
    let n := 'Sell Price' % 1;
    if n = 0 then
        'Sell Price'
    else
        if n < 0.5 then
            'Sell Price' - n + 0.5
        else
            if n > 0.5 then 'Sell Price' - n + 1 else 'Sell Price' end
        end
    end
end

but the value stored in Sell price seems to ignore it

Any suggestions