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 $23.76   5.442%   $25.053   $25.05   $25.05   $25.10  
  Purchase #2 $118.72   6.479%   $126.4119   $126.41   $126.40   $126.40  
  Purchase #3 $54.37   5.547%   $57.3859   $57.39   $57.40   $57.40  
  Purchase #4 $40.85   4.613%   $42.7344   $42.73   $42.75   $42.70  
  Purchase #5 $115.38   7.141%   $123.6193   $123.62   $123.60   $123.60  
  Purchase #6 $23.50   7.771%   $25.3262   $25.33   $25.35   $25.30  
  Purchase #7 $57.68   4.615%   $60.3419   $60.34   $60.35   $60.30  
  7 purchase totals = $434.26       $460.8726   $460.87   $460.90   $460.80