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 $82.41   5.504%   $86.9458   $86.95   $86.95   $86.90  
  Purchase #2 $205.50   5.370%   $216.5354   $216.54   $216.55   $216.50  
  Purchase #3 $88.90   10.219%   $97.9847   $97.98   $98.00   $98.00  
  Purchase #4 $80.80   8.757%   $87.8757   $87.88   $87.90   $87.90  
  Purchase #5 $49.54   4.160%   $51.6009   $51.60   $51.60   $51.60  
  Purchase #6 $77.61   5.173%   $81.6248   $81.62   $81.60   $81.60  
  Purchase #7 $182.27   6.537%   $194.185   $194.19   $194.20   $194.20  
  7 purchase totals = $767.03       $816.7523   $816.76   $816.80   $816.70