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 $199.55   7.266%   $214.0493   $214.05   $214.05   $214.00  
  Purchase #2 $204.74   4.663%   $214.287   $214.29   $214.30   $214.30  
  Purchase #3 $183.60   7.252%   $196.9147   $196.91   $196.90   $196.90  
  Purchase #4 $21.88   7.615%   $23.5462   $23.55   $23.55   $23.50  
  Purchase #5 $226.93   8.827%   $246.9611   $246.96   $246.95   $247.00  
  Purchase #6 $248.32   8.585%   $269.6383   $269.64   $269.65   $269.60  
  Purchase #7 $94.54   7.611%   $101.7354   $101.74   $101.75   $101.70  
  7 purchase totals = $1,179.56       $1,267.1320   $1,267.14   $1,267.15   $1,267.00