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 $116.26   5.401%   $122.5392   $122.54   $122.55   $122.50  
  Purchase #2 $28.41   6.581%   $30.2797   $30.28   $30.30   $30.30  
  Purchase #3 $244.58   6.323%   $260.0448   $260.04   $260.05   $260.00  
  Purchase #4 $244.26   9.266%   $266.8931   $266.89   $266.90   $266.90  
  Purchase #5 $107.66   7.626%   $115.8702   $115.87   $115.85   $115.90  
  Purchase #6 $184.51   5.138%   $193.9901   $193.99   $194.00   $194.00  
  Purchase #7 $109.67   5.831%   $116.0649   $116.06   $116.05   $116.10  
  7 purchase totals = $1,035.35       $1,105.6820   $1,105.67   $1,105.70   $1,105.70