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 $43.42   5.856%   $45.9627   $45.96   $45.95   $46.00  
  Purchase #2 $197.49   4.486%   $206.3494   $206.35   $206.35   $206.30  
  Purchase #3 $45.86   12.766%   $51.7145   $51.71   $51.70   $51.70  
  Purchase #4 $102.76   4.574%   $107.4602   $107.46   $107.45   $107.50  
  Purchase #5 $32.64   6.431%   $34.7391   $34.74   $34.75   $34.70  
  Purchase #6 $85.66   13.626%   $97.332   $97.33   $97.35   $97.30  
  Purchase #7 $205.35   3.208%   $211.9376   $211.94   $211.95   $211.90  
  7 purchase totals = $713.18       $755.4955   $755.49   $755.50   $755.40