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 $88.30   7.849%   $95.2307   $95.23   $95.25   $95.20  
  Purchase #2 $201.47   10.663%   $222.9527   $222.95   $222.95   $223.00  
  Purchase #3 $182.49   8.441%   $197.894   $197.89   $197.90   $197.90  
  Purchase #4 $237.50   4.788%   $248.8715   $248.87   $248.85   $248.90  
  Purchase #5 $197.87   3.620%   $205.0329   $205.03   $205.05   $205.00  
  Purchase #6 $238.53   3.119%   $245.9698   $245.97   $245.95   $246.00  
  Purchase #7 $239.81   7.384%   $257.5176   $257.52   $257.50   $257.50  
  7 purchase totals = $1,385.97       $1,473.4692   $1,473.46   $1,473.45   $1,473.50