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 $108.36   5.668%   $114.5018   $114.50   $114.50   $114.50  
  Purchase #2 $229.70   9.169%   $250.7612   $250.76   $250.75   $250.80  
  Purchase #3 $86.56   10.650%   $95.7786   $95.78   $95.80   $95.80  
  Purchase #4 $6.81   3.487%   $7.0475   $7.05   $7.05   $7.00  
  Purchase #5 $85.71   6.874%   $91.6017   $91.60   $91.60   $91.60  
  Purchase #6 $239.57   10.177%   $263.951   $263.95   $263.95   $264.00  
  Purchase #7 $55.64   10.356%   $61.4021   $61.40   $61.40   $61.40  
  7 purchase totals = $812.35       $885.0439   $885.04   $885.05   $885.10