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 $82.88   13.361%   $93.9536   $93.95   $93.95   $94.00  
  Purchase #2 $195.71   7.794%   $210.9636   $210.96   $210.95   $211.00  
  Purchase #3 $39.26   4.416%   $40.9937   $40.99   $41.00   $41.00  
  Purchase #4 $70.95   5.547%   $74.8856   $74.89   $74.90   $74.90  
  Purchase #5 $35.66   3.141%   $36.7801   $36.78   $36.80   $36.80  
  Purchase #6 $37.79   9.642%   $41.4337   $41.43   $41.45   $41.40  
  Purchase #7 $218.31   7.164%   $233.9497   $233.95   $233.95   $233.90  
  7 purchase totals = $680.56       $732.9600   $732.95   $733.00   $733.00