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 $105.94   8.107%   $114.5286   $114.53   $114.55   $114.50  
  Purchase #2 $179.30   5.563%   $189.2745   $189.27   $189.25   $189.30  
  Purchase #3 $115.83   10.619%   $128.13   $128.13   $128.15   $128.10  
  Purchase #4 $63.69   12.389%   $71.5806   $71.58   $71.60   $71.60  
  Purchase #5 $203.85   8.368%   $220.9082   $220.91   $220.90   $220.90  
  Purchase #6 $120.26   7.371%   $129.1244   $129.12   $129.10   $129.10  
  Purchase #7 $152.66   5.131%   $160.493   $160.49   $160.50   $160.50  
  7 purchase totals = $941.53       $1,014.0393   $1,014.03   $1,014.05   $1,014.00