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 $87.68   8.287%   $94.946   $94.95   $94.95   $94.90  
  Purchase #2 $134.62   8.763%   $146.4168   $146.42   $146.40   $146.40  
  Purchase #3 $152.70   6.509%   $162.6392   $162.64   $162.65   $162.60  
  Purchase #4 $218.38   7.422%   $234.5882   $234.59   $234.60   $234.60  
  Purchase #5 $200.91   6.698%   $214.367   $214.37   $214.35   $214.40  
  Purchase #6 $118.80   11.806%   $132.8255   $132.83   $132.85   $132.80  
  Purchase #7 $173.64   7.347%   $186.3973   $186.40   $186.40   $186.40  
  7 purchase totals = $1,086.73       $1,172.1800   $1,172.20   $1,172.20   $1,172.10