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 $84.61   13.463%   $96.001   $96.00   $96.00   $96.00  
  Purchase #2 $205.80   5.805%   $217.7467   $217.75   $217.75   $217.70  
  Purchase #3 $110.66   5.625%   $116.8846   $116.88   $116.90   $116.90  
  Purchase #4 $155.46   12.399%   $174.7355   $174.74   $174.75   $174.70  
  Purchase #5 $109.66   9.354%   $119.9176   $119.92   $119.90   $119.90  
  Purchase #6 $73.78   3.150%   $76.1041   $76.10   $76.10   $76.10  
  Purchase #7 $61.47   7.698%   $66.202   $66.20   $66.20   $66.20  
  7 purchase totals = $801.44       $867.5915   $867.59   $867.60   $867.50