Make them an offer they can't refuse.
– Don Vito
P.S. Use forum search for thread "Auktuma's Charitable Tier Upgrading".
Lvl 59 Tier Upgrader:
For tier I you will have up to 24.05% materials returned,
for tier II - up to 22.71%,
for tier III - up to 21.38%,
for tier IV - up to 20.04%
for tier V - up to 18.71%
Not too sure if that info is outdated, but gives you a picture.