[Koha] Defining Issuing Rules - fines

Hi All, I am working my way through setting the parameters in Koha. I am at the screen headed Defining Issuing Rules. I am not going to be charging any fines at my library. Should I leave the "Fines" fields on this screen blank, or fill something in like 0,0,0? Any responses appreciated. Many thanks, Jenny Collery IPPA, The Early Childhood Organisation<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />