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 $88.29   7.599%   $94.9992   $95.00   $95.00   $95.00  
  Purchase #2 $112.92   3.656%   $117.0484   $117.05   $117.05   $117.00  
  Purchase #3 $51.94   9.183%   $56.7097   $56.71   $56.70   $56.70  
  Purchase #4 $100.55   12.113%   $112.7296   $112.73   $112.75   $112.70  
  Purchase #5 $216.60   7.854%   $233.6118   $233.61   $233.60   $233.60  
  Purchase #6 $188.39   12.587%   $212.1026   $212.10   $212.10   $212.10  
  Purchase #7 $70.37   11.547%   $78.4956   $78.50   $78.50   $78.50  
  7 purchase totals = $829.06       $905.6969   $905.70   $905.70   $905.60