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 $200.25   4.133%   $208.5263   $208.53   $208.55   $208.50  
  Purchase #2 $32.37   11.218%   $36.0013   $36.00   $36.00   $36.00  
  Purchase #3 $108.94   4.645%   $114.0003   $114.00   $114.00   $114.00  
  Purchase #4 $230.31   5.470%   $242.908   $242.91   $242.90   $242.90  
  Purchase #5 $83.59   4.350%   $87.2262   $87.23   $87.25   $87.20  
  Purchase #6 $217.42   4.559%   $227.3322   $227.33   $227.35   $227.30  
  Purchase #7 $209.41   11.283%   $233.0377   $233.04   $233.05   $233.00  
  7 purchase totals = $1,082.29       $1,149.0320   $1,149.04   $1,149.10   $1,148.90