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 $176.65   5.716%   $186.7473   $186.75   $186.75   $186.70  
  Purchase #2 $248.86   4.338%   $259.6555   $259.66   $259.65   $259.70  
  Purchase #3 $142.93   13.788%   $162.6372   $162.64   $162.65   $162.60  
  Purchase #4 $10.66   8.683%   $11.5856   $11.59   $11.60   $11.60  
  Purchase #5 $151.38   4.714%   $158.5161   $158.52   $158.50   $158.50  
  Purchase #6 $209.36   5.508%   $220.8915   $220.89   $220.90   $220.90  
  Purchase #7 $85.64   11.741%   $95.695   $95.70   $95.70   $95.70  
  7 purchase totals = $1,025.48       $1,095.7282   $1,095.75   $1,095.75   $1,095.70