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 $58.85   7.418%   $63.2155   $63.22   $63.20   $63.20  
  Purchase #2 $197.42   8.484%   $214.1691   $214.17   $214.15   $214.20  
  Purchase #3 $222.74   9.767%   $244.495   $244.50   $244.50   $244.50  
  Purchase #4 $34.40   5.454%   $36.2762   $36.28   $36.30   $36.30  
  Purchase #5 $177.77   6.839%   $189.9277   $189.93   $189.95   $189.90  
  Purchase #6 $175.73   10.691%   $194.5173   $194.52   $194.50   $194.50  
  Purchase #7 $168.63   13.711%   $191.7509   $191.75   $191.75   $191.80  
  7 purchase totals = $1,035.54       $1,134.3517   $1,134.37   $1,134.35   $1,134.40