How to round down savings interest that comes from multiple savings accounts.

I know that one rounds down bank savings interest to a whole pound value when filling in the self assessment form. But when interest is earned from multiple savings accounts should one round each amount down then add those values together; or should one sum all the amounts first then round down that total?

Very depressing that nobody can be bothered to help my question. So how am I supposed to fill in my SA correctly?

Hi Alan2023,
You would round down each account and then report the total. 
Thank you.