Before the issuance of any original process in a civil action, the plaintiff shall deposit with the clerk a sum that the clerk has previously established as adequate to pay the usual costs, including litigation taxes as calculated in accordance with §8-21-401, and any local litigation tax as authorized by a private act. The clerk may allow a cost bond with adequate security in the amount of five hundred dollars ($500); provided, that any eligible plaintiff may proceed on a pauper's oath instead of the cash deposit or cost bond.