For example Paypal has a fees of 2.5%+.25

If someone send me 5$ i'll recieve
5-((5*2.5/100)+0.25) = 4.625

but how do i convert the recieved money 4.625 back to 5

i tried 4.625*102.5/100 +.25=4.99 but i want an exact value

how can that be possible?