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 $69.38   3.224%   $71.6168   $71.62   $71.60   $71.60  
  Purchase #2 $55.25   11.789%   $61.7634   $61.76   $61.75   $61.80  
  Purchase #3 $147.76   4.246%   $154.0339   $154.03   $154.05   $154.00  
  Purchase #4 $146.56   10.379%   $161.7715   $161.77   $161.75   $161.80  
  Purchase #5 $232.39   6.575%   $247.6696   $247.67   $247.65   $247.70  
  Purchase #6 $234.76   4.135%   $244.4673   $244.47   $244.45   $244.50  
  Purchase #7 $230.80   9.464%   $252.6429   $252.64   $252.65   $252.60  
  7 purchase totals = $1,116.90       $1,193.9654   $1,193.96   $1,193.90   $1,194.00