Change randbetween amount in code

Hello code experts
I have this code which displays amount with randbetween varying from 100-9900 in the extract sheet. I need your help to edit the code and change the randbetween amount to 50250-99500. I also want the figures to be round off like 50250, 51000, 51750, etc., and not 50251,50252, and so on.