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 $58.62   4.232%   $61.1008   $61.10   $61.10   $61.10  
  Purchase #2 $182.91   8.582%   $198.6073   $198.61   $198.60   $198.60  
  Purchase #3 $209.60   5.150%   $220.3944   $220.39   $220.40   $220.40  
  Purchase #4 $227.75   3.695%   $236.1654   $236.17   $236.15   $236.20  
  Purchase #5 $115.27   3.223%   $118.9852   $118.99   $119.00   $119.00  
  Purchase #6 $138.72   12.430%   $155.9629   $155.96   $155.95   $156.00  
  Purchase #7 $107.80   4.567%   $112.7232   $112.72   $112.70   $112.70  
  7 purchase totals = $1,040.67       $1,103.9392   $1,103.94   $1,103.90   $1,104.00