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 $59.68   5.474%   $62.9469   $62.95   $62.95   $62.90  
  Purchase #2 $84.61   9.130%   $92.3349   $92.33   $92.35   $92.30  
  Purchase #3 $232.41   13.462%   $263.697   $263.70   $263.70   $263.70  
  Purchase #4 $151.50   3.833%   $157.307   $157.31   $157.30   $157.30  
  Purchase #5 $184.60   11.232%   $205.3343   $205.33   $205.35   $205.30  
  Purchase #6 $130.46   3.254%   $134.7052   $134.71   $134.70   $134.70  
  Purchase #7 $144.45   4.615%   $151.1164   $151.12   $151.10   $151.10  
  7 purchase totals = $987.71       $1,067.4417   $1,067.45   $1,067.45   $1,067.30