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 $246.74   5.834%   $261.1348   $261.13   $261.15   $261.10  
  Purchase #2 $91.71   4.672%   $95.9947   $95.99   $96.00   $96.00  
  Purchase #3 $10.43   12.415%   $11.7249   $11.72   $11.70   $11.70  
  Purchase #4 $209.90   3.364%   $216.961   $216.96   $216.95   $217.00  
  Purchase #5 $42.98   12.195%   $48.2214   $48.22   $48.20   $48.20  
  Purchase #6 $248.89   7.673%   $267.9873   $267.99   $268.00   $268.00  
  Purchase #7 $179.76   7.741%   $193.6752   $193.68   $193.70   $193.70  
  7 purchase totals = $1,030.41       $1,095.6993   $1,095.69   $1,095.70   $1,095.70