Did you know Sharp makes a couple lines of commercial grade cash registers. The commercial grade register's model numbers begin with ER or UP. Sharp makes a line called the XE line which is consumer grade and while they have some nice features they are not heavy duty like the ER and UP models.

The ER and UP line includes the following

• Sharp ER-A320 Cash Register
• Sharp ER-A330 Cash Register
• Sharp ER-A410 Cash Register
• Sharp ER-A420 Cash Register
• Sharp ER-A440 Cash Register
• Sharp ER-A450T Cash Register
• Sharp ER-A520 Cash Register
• Sharp ER-A530 Cash Register
• Sharp UP-700 Cash Register
• Sharp UP-820F Cash Register
• Sharp UP-820N Cash Register

Don't forget the XE line are not the same quality as the ER and UP models. Taken care of a good commercial grade cash register should last in a normal busy business about 5 to 7 years of course there are exceptions in both directions!