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 $88.34   8.104%   $95.4991   $95.50   $95.50   $95.50  
  Purchase #2 $191.82   11.654%   $214.1747   $214.17   $214.15   $214.20  
  Purchase #3 $5.63   8.110%   $6.0866   $6.09   $6.10   $6.10  
  Purchase #4 $168.63   7.407%   $181.1204   $181.12   $181.10   $181.10  
  Purchase #5 $151.46   13.234%   $171.5042   $171.50   $171.50   $171.50  
  Purchase #6 $195.85   5.526%   $206.6727   $206.67   $206.65   $206.70  
  Purchase #7 $69.60   8.560%   $75.5578   $75.56   $75.55   $75.60  
  7 purchase totals = $871.33       $950.6155   $950.61   $950.55   $950.70