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 $68.74   3.362%   $71.051   $71.05   $71.05   $71.10  
  Purchase #2 $184.30   12.694%   $207.695   $207.70   $207.70   $207.70  
  Purchase #3 $56.45   7.450%   $60.6555   $60.66   $60.65   $60.70  
  Purchase #4 $227.36   8.502%   $246.6901   $246.69   $246.70   $246.70  
  Purchase #5 $232.78   6.408%   $247.6965   $247.70   $247.70   $247.70  
  Purchase #6 $37.43   6.422%   $39.8338   $39.83   $39.85   $39.80  
  Purchase #7 $139.33   9.768%   $152.9398   $152.94   $152.95   $152.90  
  7 purchase totals = $946.39       $1,026.5617   $1,026.57   $1,026.60   $1,026.60