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 $88.25   7.665%   $95.0144   $95.01   $95.00   $95.00  
  Purchase #2 $9.80   8.398%   $10.623   $10.62   $10.60   $10.60  
  Purchase #3 $154.26   12.763%   $173.9482   $173.95   $173.95   $173.90  
  Purchase #4 $161.55   4.434%   $168.7131   $168.71   $168.70   $168.70  
  Purchase #5 $152.43   5.445%   $160.7298   $160.73   $160.75   $160.70  
  Purchase #6 $96.79   5.827%   $102.43   $102.43   $102.45   $102.40  
  Purchase #7 $69.30   10.831%   $76.8059   $76.81   $76.80   $76.80  
  7 purchase totals = $732.38       $788.2644   $788.26   $788.25   $788.10