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 $69.51   10.702%   $76.949   $76.95   $76.95   $76.90  
  Purchase #2 $181.74   6.754%   $194.0147   $194.01   $194.00   $194.00  
  Purchase #3 $69.28   7.766%   $74.6603   $74.66   $74.65   $74.70  
  Purchase #4 $244.88   4.606%   $256.1592   $256.16   $256.15   $256.20  
  Purchase #5 $41.43   9.299%   $45.2826   $45.28   $45.30   $45.30  
  Purchase #6 $248.75   4.344%   $259.5557   $259.56   $259.55   $259.60  
  Purchase #7 $176.75   7.458%   $189.932   $189.93   $189.95   $189.90  
  7 purchase totals = $1,032.34       $1,096.5535   $1,096.55   $1,096.55   $1,096.60