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 $86.90   9.283%   $94.9669   $94.97   $94.95   $95.00  
  Purchase #2 $242.84   8.302%   $263.0006   $263.00   $263.00   $263.00  
  Purchase #3 $9.81   4.426%   $10.2442   $10.24   $10.25   $10.20  
  Purchase #4 $250.66   6.419%   $266.7499   $266.75   $266.75   $266.70  
  Purchase #5 $203.34   6.797%   $217.161   $217.16   $217.15   $217.20  
  Purchase #6 $189.97   11.223%   $211.2903   $211.29   $211.30   $211.30  
  Purchase #7 $224.49   13.780%   $255.4247   $255.42   $255.40   $255.40  
  7 purchase totals = $1,208.01       $1,318.8376   $1,318.83   $1,318.80   $1,318.80