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 $119.33   5.227%   $125.5674   $125.57   $125.55   $125.60  
  Purchase #2 $211.79   10.816%   $234.6972   $234.70   $234.70   $234.70  
  Purchase #3 $79.85   10.338%   $88.1049   $88.10   $88.10   $88.10  
  Purchase #4 $186.66   11.448%   $208.0288   $208.03   $208.05   $208.00  
  Purchase #5 $154.38   5.161%   $162.3476   $162.35   $162.35   $162.30  
  Purchase #6 $74.28   4.647%   $77.7318   $77.73   $77.75   $77.70  
  Purchase #7 $68.62   12.659%   $77.3066   $77.31   $77.30   $77.30  
  7 purchase totals = $894.91       $973.7843   $973.79   $973.80   $973.70