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 $91.55   3.719%   $94.9547   $94.95   $94.95   $95.00  
  Purchase #2 $176.88   8.290%   $191.5434   $191.54   $191.55   $191.50  
  Purchase #3 $52.69   3.270%   $54.413   $54.41   $54.40   $54.40  
  Purchase #4 $212.88   11.281%   $236.895   $236.90   $236.90   $236.90  
  Purchase #5 $34.47   4.305%   $35.9539   $35.95   $35.95   $36.00  
  Purchase #6 $8.77   4.832%   $9.1938   $9.19   $9.20   $9.20  
  Purchase #7 $176.45   10.221%   $194.485   $194.49   $194.50   $194.50  
  7 purchase totals = $753.69       $817.4388   $817.43   $817.45   $817.50