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 $152.76   5.364%   $160.954   $160.95   $160.95   $161.00  
  Purchase #2 $104.73   10.715%   $115.9518   $115.95   $115.95   $116.00  
  Purchase #3 $64.47   6.216%   $68.4775   $68.48   $68.50   $68.50  
  Purchase #4 $78.64   13.709%   $89.4208   $89.42   $89.40   $89.40  
  Purchase #5 $156.68   8.432%   $169.8913   $169.89   $169.90   $169.90  
  Purchase #6 $95.41   6.862%   $101.957   $101.96   $101.95   $102.00  
  Purchase #7 $135.94   13.147%   $153.812   $153.81   $153.80   $153.80  
  7 purchase totals = $788.63       $860.4644   $860.46   $860.45   $860.60