Is there a way my boss's could have messed up my taxes ? Some look strange from year to year

[VolvoGirl]

For federal withholding?  Each year is separate and changes.  There have been major tax changes the last 3 years.

For one thing the IRS changed the withholding tables so you got more in your checks during the year instead of a big refund.  Or there are other tax changes.  And any  dependents you have are a year older.  If you made more income that can reduce some credits you got like the EIC.  

[bbgun]

If things look strange you should take it to your Company HR department for clarification.