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 $62.95   12.801%   $71.0082   $71.01   $71.00   $71.00  
  Purchase #2 $240.86   4.509%   $251.7204   $251.72   $251.70   $251.70  
  Purchase #3 $133.64   8.796%   $145.395   $145.40   $145.40   $145.40  
  Purchase #4 $232.35   5.323%   $244.718   $244.72   $244.70   $244.70  
  Purchase #5 $175.68   10.298%   $193.7715   $193.77   $193.75   $193.80  
  Purchase #6 $199.75   5.655%   $211.0459   $211.05   $211.05   $211.00  
  Purchase #7 $214.83   12.506%   $241.6966   $241.70   $241.70   $241.70  
  7 purchase totals = $1,260.06       $1,359.3556   $1,359.37   $1,359.30   $1,359.30