All calculations are performed and rounded to six decimal places and then displayed to you rounded to two decimal places. This can mean that you sometimes are unable to invest the last penny in your account because the actual amount is less than a full penny but has been rounded up for display purposes.
Regardless of what yield you are shown, loan calculations are always based upon the price that you enter. In the event of a discrepancy between yield and price, price always prevails.
The calculation of an AER is done on an iterative basis and so the actual solution to the equation may vary. In testing, our results have always been accurate to 0.001% which means that unless you are trading in size of £10,000 or more per loan, any rounding will probably not show up.