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 $88.26   7.523%   $94.8998   $94.90   $94.90   $94.90  
  Purchase #2 $187.89   10.453%   $207.5301   $207.53   $207.55   $207.50  
  Purchase #3 $196.40   5.227%   $206.6658   $206.67   $206.65   $206.70  
  Purchase #4 $88.44   6.422%   $94.1196   $94.12   $94.10   $94.10  
  Purchase #5 $192.60   3.846%   $200.0074   $200.01   $200.00   $200.00  
  Purchase #6 $22.76   6.257%   $24.1841   $24.18   $24.20   $24.20  
  Purchase #7 $34.98   4.586%   $36.5842   $36.58   $36.60   $36.60  
  7 purchase totals = $811.33       $863.9910   $863.99   $864.00   $864.00