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 $62.77   11.434%   $69.9471   $69.95   $69.95   $69.90  
  Purchase #2 $227.48   5.516%   $240.0278   $240.03   $240.05   $240.00  
  Purchase #3 $233.49   10.252%   $257.4274   $257.43   $257.45   $257.40  
  Purchase #4 $192.44   6.859%   $205.6395   $205.64   $205.65   $205.60  
  Purchase #5 $246.58   12.624%   $277.7083   $277.71   $277.70   $277.70  
  Purchase #6 $51.63   8.559%   $56.049   $56.05   $56.05   $56.00  
  Purchase #7 $243.54   5.695%   $257.4096   $257.41   $257.40   $257.40  
  7 purchase totals = $1,257.93       $1,364.2087   $1,364.22   $1,364.25   $1,364.00