Kansas POS Tax Issues

[RindLady]

We have tax applied to all applicable items for instance drinks.  Up until 1:30 pm today tax was calculated at the time we are checking customers out on the POS.  The same 44 oz drink that rang out for $2.17 at 9 a.m. today is ringing out at $1.79 today for some reason. No one is overriding the tax or removing the tax.  My staff doesn't have access to even do that.  

There has to be a bug in the system it's taking tax off of some and not off of others.  Any ideas?