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 $87.95   8.863%   $95.745   $95.75   $95.75   $95.70  
  Purchase #2 $5.47   4.849%   $5.7352   $5.74   $5.75   $5.70  
  Purchase #3 $145.69   8.313%   $157.8012   $157.80   $157.80   $157.80  
  Purchase #4 $43.84   9.283%   $47.9097   $47.91   $47.90   $47.90  
  Purchase #5 $177.72   11.583%   $198.3053   $198.31   $198.30   $198.30  
  Purchase #6 $124.26   5.233%   $130.7625   $130.76   $130.75   $130.80  
  Purchase #7 $224.55   5.231%   $236.2962   $236.30   $236.30   $236.30  
  7 purchase totals = $809.48       $872.5551   $872.57   $872.55   $872.50