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 $86.68   9.577%   $94.9813   $94.98   $95.00   $95.00  
  Purchase #2 $67.95   3.726%   $70.4818   $70.48   $70.50   $70.50  
  Purchase #3 $207.26   4.220%   $216.0064   $216.01   $216.00   $216.00  
  Purchase #4 $5.37   5.340%   $5.6568   $5.66   $5.65   $5.70  
  Purchase #5 $234.63   8.801%   $255.2798   $255.28   $255.30   $255.30  
  Purchase #6 $218.52   5.779%   $231.1483   $231.15   $231.15   $231.10  
  Purchase #7 $216.38   13.540%   $245.6779   $245.68   $245.70   $245.70  
  7 purchase totals = $1,036.79       $1,119.2323   $1,119.24   $1,119.30   $1,119.30