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 $181.50   7.355%   $194.8493   $194.85   $194.85   $194.80  
  Purchase #2 $53.71   8.321%   $58.1792   $58.18   $58.20   $58.20  
  Purchase #3 $248.74   7.355%   $267.0348   $267.03   $267.05   $267.00  
  Purchase #4 $40.25   3.618%   $41.7062   $41.71   $41.70   $41.70  
  Purchase #5 $65.33   7.509%   $70.2356   $70.24   $70.25   $70.20  
  Purchase #6 $154.30   5.628%   $162.984   $162.98   $163.00   $163.00  
  Purchase #7 $198.74   11.296%   $221.1897   $221.19   $221.20   $221.20  
  7 purchase totals = $942.57       $1,016.1788   $1,016.18   $1,016.25   $1,016.10