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 $43.44   7.707%   $46.7879   $46.79   $46.80   $46.80  
  Purchase #2 $246.94   7.533%   $265.542   $265.54   $265.55   $265.50  
  Purchase #3 $67.64   3.235%   $69.8282   $69.83   $69.85   $69.80  
  Purchase #4 $163.78   3.407%   $169.36   $169.36   $169.35   $169.40  
  Purchase #5 $248.60   6.412%   $264.5402   $264.54   $264.55   $264.50  
  Purchase #6 $48.88   13.216%   $55.34   $55.34   $55.35   $55.30  
  Purchase #7 $144.73   11.787%   $161.7893   $161.79   $161.80   $161.80  
  7 purchase totals = $964.01       $1,033.1876   $1,033.19   $1,033.25   $1,033.10