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 $84.32   13.393%   $95.613   $95.61   $95.60   $95.60  
  Purchase #2 $229.58   7.183%   $246.0707   $246.07   $246.05   $246.10  
  Purchase #3 $67.25   12.441%   $75.6166   $75.62   $75.60   $75.60  
  Purchase #4 $133.35   6.416%   $141.9057   $141.91   $141.90   $141.90  
  Purchase #5 $114.49   3.464%   $118.4559   $118.46   $118.45   $118.50  
  Purchase #6 $196.81   6.628%   $209.8546   $209.85   $209.85   $209.90  
  Purchase #7 $249.96   12.772%   $281.8849   $281.88   $281.90   $281.90  
  7 purchase totals = $1,075.76       $1,169.4014   $1,169.40   $1,169.35   $1,169.50