Canterbury Tales Riddle

http://www.timetravel-britain.com/06...03-Chaucer.jpg

Four pilgrims were on the road to Canterbury. Their names, in no particular order, were John, Geoffrey, Martin, and Stephen. This is the conversation they had on the road:

John: “I usually only tithe two pence, but if I beat Stephen to Canterbury, I’ll gladly tithe double!”
Martin: “If I get to Canterbury first, I shall show my gratitude by tithing six pence! If I don’t, I shall tithe 4 pence anyway.”
Stephen: “You wayward fools are tossed by the wind! No matter what happens before here and Canterbury, I shall tithe three pence only. Heaven forgive your false piety!”
Geoffrey: “Shut up, Stephen. I pledge three pence if I beat you to Canterbury, but nothing if I don’t. We’ll see who’s right!”

Everybody was true to his word, and a total of thirteen pence was tithed at Canterbury. In what order did the pilgrims arrive?
Good luck!

FYI: for all of you who think “what the … is a tithe? A tithe (from Old English teogoþa “tenth”) is a one-tenth part of something, paid as a (usually) voluntary contribution or as a tax or levy, usually to support a Jewish or Christian religious organization.