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 $201.77   7.521%   $216.9451   $216.95   $216.95   $216.90  
  Purchase #2 $45.77   3.422%   $47.3362   $47.34   $47.35   $47.30  
  Purchase #3 $246.72   5.670%   $260.709   $260.71   $260.70   $260.70  
  Purchase #4 $35.43   6.480%   $37.7259   $37.73   $37.75   $37.70  
  Purchase #5 $192.64   11.342%   $214.4892   $214.49   $214.50   $214.50  
  Purchase #6 $52.68   6.546%   $56.1284   $56.13   $56.15   $56.10  
  Purchase #7 $207.88   13.795%   $236.557   $236.56   $236.55   $236.60  
  7 purchase totals = $982.89       $1,069.8908   $1,069.91   $1,069.95   $1,069.80