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 $214.46   8.679%   $233.073   $233.07   $233.05   $233.10  
  Purchase #2 $68.40   6.174%   $72.623   $72.62   $72.60   $72.60  
  Purchase #3 $208.37   6.753%   $222.4412   $222.44   $222.45   $222.40  
  Purchase #4 $199.47   7.215%   $213.8618   $213.86   $213.85   $213.90  
  Purchase #5 $192.70   5.448%   $203.1983   $203.20   $203.20   $203.20  
  Purchase #6 $42.55   8.119%   $46.0046   $46.00   $46.00   $46.00  
  Purchase #7 $243.98   13.106%   $275.956   $275.96   $275.95   $276.00  
  7 purchase totals = $1,169.93       $1,267.1579   $1,267.15   $1,267.10   $1,267.20