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 $72.55   5.230%   $76.3444   $76.34   $76.35   $76.30  
  Purchase #2 $8.88   8.271%   $9.6145   $9.61   $9.60   $9.60  
  Purchase #3 $147.49   5.801%   $156.0459   $156.05   $156.05   $156.00  
  Purchase #4 $229.47   5.163%   $241.3175   $241.32   $241.30   $241.30  
  Purchase #5 $239.94   9.340%   $262.3504   $262.35   $262.35   $262.40  
  Purchase #6 $244.84   8.531%   $265.7273   $265.73   $265.75   $265.70  
  Purchase #7 $80.48   3.698%   $83.4562   $83.46   $83.45   $83.50  
  7 purchase totals = $1,023.65       $1,094.8562   $1,094.86   $1,094.85   $1,094.80