Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $205.46   4.455%   $214.6132   $214.61   $214.60   $214.60  
  Purchase #2 $229.96   11.164%   $255.6327   $255.63   $255.65   $255.60  
  Purchase #3 $234.29   4.364%   $244.5144   $244.51   $244.50   $244.50  
  Purchase #4 $182.50   3.256%   $188.4422   $188.44   $188.45   $188.40  
  Purchase #5 $142.76   3.644%   $147.9622   $147.96   $147.95   $148.00  
  Purchase #6 $160.53   9.335%   $175.5155   $175.52   $175.50   $175.50  
  Purchase #7 $208.73   12.257%   $234.314   $234.31   $234.30   $234.30  
  7 purchase totals = $1,364.23       $1,460.9942   $1,460.98   $1,460.95   $1,460.90