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 $85.53   12.177%   $95.945   $95.95   $95.95   $95.90  
  Purchase #2 $194.68   10.313%   $214.7573   $214.76   $214.75   $214.80  
  Purchase #3 $110.76   7.487%   $119.0526   $119.05   $119.05   $119.10  
  Purchase #4 $92.95   5.598%   $98.1533   $98.15   $98.15   $98.20  
  Purchase #5 $148.78   10.348%   $164.1758   $164.18   $164.20   $164.20  
  Purchase #6 $126.37   6.176%   $134.1746   $134.17   $134.15   $134.20  
  Purchase #7 $230.30   8.201%   $249.1869   $249.19   $249.20   $249.20  
  7 purchase totals = $989.37       $1,075.4455   $1,075.45   $1,075.45   $1,075.60