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 $61.25   13.708%   $69.6462   $69.65   $69.65   $69.60  
  Purchase #2 $173.62   13.814%   $197.6039   $197.60   $197.60   $197.60  
  Purchase #3 $189.49   6.156%   $201.155   $201.16   $201.15   $201.20  
  Purchase #4 $195.86   8.603%   $212.7098   $212.71   $212.70   $212.70  
  Purchase #5 $135.50   13.309%   $153.5337   $153.53   $153.55   $153.50  
  Purchase #6 $37.42   6.427%   $39.825   $39.83   $39.85   $39.80  
  Purchase #7 $75.38   6.456%   $80.2465   $80.25   $80.25   $80.20  
  7 purchase totals = $868.52       $954.7201   $954.73   $954.75   $954.60