Square unfortunatly, calculates sales tax as  "bankers rounding" 

In other words, if the total cost is 299.954, Square rounds it to 299.95 instead of 299.96. This usually results in you being that few cents shy of the sales tax you should have collected. but it actually seems like your ontop. so i kudo that for you. But either way, you have to round that number to something inorder to collect the funds. so when your at the end of the week and calculate total sales tax on gross goods vs what was collected. it will be different.