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 $62.61   10.212%   $69.0037   $69.00   $69.00   $69.00  
  Purchase #2 $209.67   3.723%   $217.476   $217.48   $217.50   $217.50  
  Purchase #3 $244.96   9.819%   $269.0126   $269.01   $269.00   $269.00  
  Purchase #4 $140.40   12.395%   $157.8026   $157.80   $157.80   $157.80  
  Purchase #5 $62.50   6.567%   $66.6044   $66.60   $66.60   $66.60  
  Purchase #6 $70.63   4.774%   $74.0019   $74.00   $74.00   $74.00  
  Purchase #7 $181.43   9.743%   $199.1067   $199.11   $199.10   $199.10  
  7 purchase totals = $972.20       $1,053.0079   $1,053.00   $1,053.00   $1,053.00