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 $55.30   13.452%   $62.739   $62.74   $62.75   $62.70  
  Purchase #2 $142.83   9.344%   $156.176   $156.18   $156.20   $156.20  
  Purchase #3 $236.75   3.547%   $245.1475   $245.15   $245.15   $245.10  
  Purchase #4 $199.27   3.647%   $206.5374   $206.54   $206.55   $206.50  
  Purchase #5 $233.50   13.660%   $265.3961   $265.40   $265.40   $265.40  
  Purchase #6 $101.60   12.480%   $114.2797   $114.28   $114.30   $114.30  
  Purchase #7 $62.45   10.452%   $68.9773   $68.98   $69.00   $69.00  
  7 purchase totals = $1,031.70       $1,119.2530   $1,119.27   $1,119.35   $1,119.20