depends on the size of your order.
example
stock A 9.99/10.01, with 1000 shares offered at 10.01.
you buy 200 limit 10.20 -> executed @ 10.01.
but if you buy 5000 limit 10.20, you only get 1000 @ 10.01, and the rest at higher prices (if theres an offer at 10.02 of 1000 you get this another...