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 $196.56   6.447%   $209.2322   $209.23   $209.25   $209.20  
  Purchase #2 $208.98   7.483%   $224.618   $224.62   $224.60   $224.60  
  Purchase #3 $166.59   6.473%   $177.3734   $177.37   $177.35   $177.40  
  Purchase #4 $117.60   6.786%   $125.5803   $125.58   $125.60   $125.60  
  Purchase #5 $127.52   10.861%   $141.3699   $141.37   $141.35   $141.40  
  Purchase #6 $165.32   7.823%   $178.253   $178.25   $178.25   $178.30  
  Purchase #7 $9.82   12.440%   $11.0416   $11.04   $11.05   $11.00  
  7 purchase totals = $992.39       $1,067.4684   $1,067.46   $1,067.45   $1,067.50