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 $83.58   13.639%   $94.9795   $94.98   $95.00   $95.00  
  Purchase #2 $141.95   13.154%   $160.6221   $160.62   $160.60   $160.60  
  Purchase #3 $208.99   12.316%   $234.7292   $234.73   $234.75   $234.70  
  Purchase #4 $176.34   11.827%   $197.1957   $197.20   $197.20   $197.20  
  Purchase #5 $36.93   4.236%   $38.4944   $38.49   $38.50   $38.50  
  Purchase #6 $77.65   9.489%   $85.0182   $85.02   $85.00   $85.00  
  Purchase #7 $49.68   4.360%   $51.846   $51.85   $51.85   $51.80  
  7 purchase totals = $775.12       $862.8851   $862.89   $862.90   $862.80