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 $181.94   7.275%   $195.1761   $195.18   $195.20   $195.20  
  Purchase #2 $227.48   5.371%   $239.698   $239.70   $239.70   $239.70  
  Purchase #3 $67.71   11.841%   $75.7275   $75.73   $75.75   $75.70  
  Purchase #4 $153.95   10.175%   $169.6144   $169.61   $169.60   $169.60  
  Purchase #5 $65.29   3.855%   $67.8069   $67.81   $67.80   $67.80  
  Purchase #6 $187.64   10.199%   $206.7774   $206.78   $206.80   $206.80  
  Purchase #7 $101.63   11.528%   $113.3459   $113.35   $113.35   $113.30  
  7 purchase totals = $985.64       $1,068.1462   $1,068.16   $1,068.20   $1,068.10