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 $92.58   3.302%   $95.637   $95.64   $95.65   $95.60  
  Purchase #2 $236.46   11.432%   $263.4921   $263.49   $263.50   $263.50  
  Purchase #3 $25.40   5.247%   $26.7327   $26.73   $26.75   $26.70  
  Purchase #4 $192.40   4.153%   $200.3904   $200.39   $200.40   $200.40  
  Purchase #5 $208.66   10.631%   $230.8426   $230.84   $230.85   $230.80  
  Purchase #6 $23.84   12.603%   $26.8446   $26.84   $26.85   $26.80  
  Purchase #7 $43.60   12.135%   $48.8909   $48.89   $48.90   $48.90  
  7 purchase totals = $822.94       $892.8303   $892.82   $892.90   $892.70