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 $86.66   8.430%   $93.9654   $93.97   $93.95   $94.00  
  Purchase #2 $220.57   11.657%   $246.2818   $246.28   $246.30   $246.30  
  Purchase #3 $57.44   7.521%   $61.7601   $61.76   $61.75   $61.80  
  Purchase #4 $234.75   7.198%   $251.6473   $251.65   $251.65   $251.60  
  Purchase #5 $41.99   10.611%   $46.4456   $46.45   $46.45   $46.40  
  Purchase #6 $78.40   7.729%   $84.4595   $84.46   $84.45   $84.50  
  Purchase #7 $205.75   9.837%   $225.9896   $225.99   $226.00   $226.00  
  7 purchase totals = $925.56       $1,010.5493   $1,010.56   $1,010.55   $1,010.60