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 $208.25   3.382%   $215.293   $215.29   $215.30   $215.30  
  Purchase #2 $215.32   9.213%   $235.1574   $235.16   $235.15   $235.20  
  Purchase #3 $206.91   5.662%   $218.6252   $218.63   $218.65   $218.60  
  Purchase #4 $244.91   3.316%   $253.0312   $253.03   $253.05   $253.00  
  Purchase #5 $196.47   13.799%   $223.5809   $223.58   $223.60   $223.60  
  Purchase #6 $179.66   13.552%   $204.0075   $204.01   $204.00   $204.00  
  Purchase #7 $125.87   5.449%   $132.7287   $132.73   $132.75   $132.70  
  7 purchase totals = $1,377.39       $1,482.4239   $1,482.43   $1,482.50   $1,482.40