Mark, thank you!! for your help. I used your formula but in reverse order. (because many of the zip codes where Zip + 4 --- so I had to approach from the LEFT.

Formula I used

If([ZipZeroState]=true and Begins([ShipTo_Zip],"0"), Left([ShipTo_Zip],5),If([ZipZeroState]=true, Left("0" & [ShipTo_Zip],5),Left([ShipTo_Zip],5))

[ZipZeroState] Case([ShipTo_State],"CT",true,"NJ",true,"MA",true,"ME",true,"NH",true,"PR",true,"RI",true,"VT",true,"AE",true,false)

Thank you again