Automatic rates follow Tringify's current market rates. Manual rates are decimal values relative to the base currency: for example, a rate of 0.012 means one unit of the base currency converts to 0.012 units of that currency.
Price rounding is applied after conversion. It changes the displayed converted price, not the source price stored in the base currency. The base currency never uses conversion rounding.
Switching from automatic to manual rates snapshots the current rates so you can edit them. Automatic rates can be enabled only after all additional currencies have been removed.