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 $85.86   10.178%   $94.5988   $94.60   $94.60   $94.60  
  Purchase #2 $184.98   11.208%   $205.7126   $205.71   $205.70   $205.70  
  Purchase #3 $215.81   13.158%   $244.2063   $244.21   $244.20   $244.20  
  Purchase #4 $62.57   3.559%   $64.7969   $64.80   $64.80   $64.80  
  Purchase #5 $57.31   5.787%   $60.6265   $60.63   $60.65   $60.60  
  Purchase #6 $91.62   5.686%   $96.8295   $96.83   $96.85   $96.80  
  Purchase #7 $228.52   9.291%   $249.7518   $249.75   $249.75   $249.80  
  7 purchase totals = $926.67       $1,016.5224   $1,016.53   $1,016.55   $1,016.50