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 $62.26   9.138%   $67.9493   $67.95   $67.95   $67.90  
  Purchase #2 $31.43   12.403%   $35.3283   $35.33   $35.35   $35.30  
  Purchase #3 $177.92   10.190%   $196.05   $196.05   $196.05   $196.10  
  Purchase #4 $60.59   7.801%   $65.3166   $65.32   $65.30   $65.30  
  Purchase #5 $214.97   11.523%   $239.741   $239.74   $239.75   $239.70  
  Purchase #6 $223.28   11.437%   $248.8165   $248.82   $248.80   $248.80  
  Purchase #7 $199.61   7.239%   $214.0598   $214.06   $214.05   $214.10  
  7 purchase totals = $970.06       $1,067.2615   $1,067.27   $1,067.25   $1,067.20