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 $65.39   9.743%   $71.7609   $71.76   $71.75   $71.80  
  Purchase #2 $168.74   4.642%   $176.5729   $176.57   $176.55   $176.60  
  Purchase #3 $232.61   5.418%   $245.2128   $245.21   $245.20   $245.20  
  Purchase #4 $203.46   6.762%   $217.218   $217.22   $217.20   $217.20  
  Purchase #5 $192.43   10.539%   $212.7102   $212.71   $212.70   $212.70  
  Purchase #6 $76.88   3.512%   $79.58   $79.58   $79.60   $79.60  
  Purchase #7 $86.98   6.422%   $92.5659   $92.57   $92.55   $92.60  
  7 purchase totals = $1,026.49       $1,095.6207   $1,095.62   $1,095.55   $1,095.70