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 $196.80   5.332%   $207.2934   $207.29   $207.30   $207.30  
  Purchase #2 $185.97   6.243%   $197.5801   $197.58   $197.60   $197.60  
  Purchase #3 $117.56   8.251%   $127.2599   $127.26   $127.25   $127.30  
  Purchase #4 $44.82   3.678%   $46.4685   $46.47   $46.45   $46.50  
  Purchase #5 $134.82   4.291%   $140.6051   $140.61   $140.60   $140.60  
  Purchase #6 $225.61   3.449%   $233.3913   $233.39   $233.40   $233.40  
  Purchase #7 $139.41   8.317%   $151.0047   $151.00   $151.00   $151.00  
  7 purchase totals = $1,044.99       $1,103.6030   $1,103.60   $1,103.60   $1,103.70