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 $88.36   7.467%   $94.9578   $94.96   $94.95   $95.00  
  Purchase #2 $183.41   13.171%   $207.5669   $207.57   $207.55   $207.60  
  Purchase #3 $167.44   7.260%   $179.5961   $179.60   $179.60   $179.60  
  Purchase #4 $96.50   13.517%   $109.5439   $109.54   $109.55   $109.50  
  Purchase #5 $47.39   7.859%   $51.1144   $51.11   $51.10   $51.10  
  Purchase #6 $137.75   13.612%   $156.5005   $156.50   $156.50   $156.50  
  Purchase #7 $148.99   11.220%   $165.7067   $165.71   $165.70   $165.70  
  7 purchase totals = $869.84       $964.9863   $964.99   $964.95   $965.00