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 $84.80   12.861%   $95.7061   $95.71   $95.70   $95.70  
  Purchase #2 $147.83   3.636%   $153.2051   $153.21   $153.20   $153.20  
  Purchase #3 $168.60   13.242%   $190.926   $190.93   $190.95   $190.90  
  Purchase #4 $197.56   11.811%   $220.8938   $220.89   $220.90   $220.90  
  Purchase #5 $146.97   10.274%   $162.0697   $162.07   $162.05   $162.10  
  Purchase #6 $130.64   10.870%   $144.8406   $144.84   $144.85   $144.80  
  Purchase #7 $168.79   4.563%   $176.4919   $176.49   $176.50   $176.50  
  7 purchase totals = $1,045.19       $1,144.1332   $1,144.14   $1,144.15   $1,144.10