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 $83.53   13.708%   $94.9803   $94.98   $95.00   $95.00  
  Purchase #2 $73.42   13.720%   $83.4932   $83.49   $83.50   $83.50  
  Purchase #3 $30.42   4.388%   $31.7548   $31.75   $31.75   $31.80  
  Purchase #4 $181.97   6.445%   $193.698   $193.70   $193.70   $193.70  
  Purchase #5 $201.76   12.440%   $226.8589   $226.86   $226.85   $226.90  
  Purchase #6 $100.99   11.781%   $112.8876   $112.89   $112.90   $112.90  
  Purchase #7 $100.57   7.343%   $107.9549   $107.95   $107.95   $108.00  
  7 purchase totals = $772.66       $851.6277   $851.62   $851.65   $851.80