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 $86.72   9.834%   $95.248   $95.25   $95.25   $95.20  
  Purchase #2 $195.31   5.477%   $206.0071   $206.01   $206.00   $206.00  
  Purchase #3 $241.88   10.390%   $267.0113   $267.01   $267.00   $267.00  
  Purchase #4 $228.29   5.733%   $241.3779   $241.38   $241.40   $241.40  
  Purchase #5 $141.38   12.591%   $159.1812   $159.18   $159.20   $159.20  
  Purchase #6 $119.76   9.845%   $131.5504   $131.55   $131.55   $131.60  
  Purchase #7 $158.28   10.686%   $175.1938   $175.19   $175.20   $175.20  
  7 purchase totals = $1,171.62       $1,275.5697   $1,275.57   $1,275.60   $1,275.60