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 $59.50   5.747%   $62.9195   $62.92   $62.90   $62.90  
  Purchase #2 $117.51   4.834%   $123.1904   $123.19   $123.20   $123.20  
  Purchase #3 $16.34   8.141%   $17.6702   $17.67   $17.65   $17.70  
  Purchase #4 $208.54   3.234%   $215.2842   $215.28   $215.30   $215.30  
  Purchase #5 $12.76   7.559%   $13.7245   $13.72   $13.70   $13.70  
  Purchase #6 $234.97   4.751%   $246.1334   $246.13   $246.15   $246.10  
  Purchase #7 $190.25   13.796%   $216.4969   $216.50   $216.50   $216.50  
  7 purchase totals = $839.87       $895.4191   $895.41   $895.40   $895.40