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 $88.46   7.337%   $94.9503   $94.95   $94.95   $95.00  
  Purchase #2 $241.37   10.284%   $266.1925   $266.19   $266.20   $266.20  
  Purchase #3 $180.85   5.113%   $190.0969   $190.10   $190.10   $190.10  
  Purchase #4 $101.74   3.390%   $105.189   $105.19   $105.20   $105.20  
  Purchase #5 $110.55   11.290%   $123.0311   $123.03   $123.05   $123.00  
  Purchase #6 $101.98   3.783%   $105.8379   $105.84   $105.85   $105.80  
  Purchase #7 $58.99   7.470%   $63.3966   $63.40   $63.40   $63.40  
  7 purchase totals = $883.94       $948.6943   $948.70   $948.75   $948.70