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 $24.38   6.526%   $25.971   $25.97   $25.95   $26.00  
  Purchase #2 $206.66   8.440%   $224.1021   $224.10   $224.10   $224.10  
  Purchase #3 $44.76   7.709%   $48.2105   $48.21   $48.20   $48.20  
  Purchase #4 $168.76   13.789%   $192.0303   $192.03   $192.05   $192.00  
  Purchase #5 $195.83   8.161%   $211.8117   $211.81   $211.80   $211.80  
  Purchase #6 $100.97   3.238%   $104.2394   $104.24   $104.25   $104.20  
  Purchase #7 $214.86   12.803%   $242.3685   $242.37   $242.35   $242.40  
  7 purchase totals = $956.22       $1,048.7335   $1,048.73   $1,048.70   $1,048.70