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 $62.37   11.492%   $69.5376   $69.54   $69.55   $69.50  
  Purchase #2 $203.96   11.678%   $227.7784   $227.78   $227.80   $227.80  
  Purchase #3 $9.68   7.511%   $10.4071   $10.41   $10.40   $10.40  
  Purchase #4 $8.92   9.249%   $9.745   $9.75   $9.75   $9.70  
  Purchase #5 $132.27   12.293%   $148.53   $148.53   $148.55   $148.50  
  Purchase #6 $166.99   12.817%   $188.3931   $188.39   $188.40   $188.40  
  Purchase #7 $222.59   8.132%   $240.691   $240.69   $240.70   $240.70  
  7 purchase totals = $806.78       $895.0822   $895.09   $895.15   $895.00