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 $44.99   4.378%   $46.9597   $46.96   $46.95   $47.00  
  Purchase #2 $171.53   7.413%   $184.2455   $184.25   $184.25   $184.20  
  Purchase #3 $145.39   6.354%   $154.6281   $154.63   $154.65   $154.60  
  Purchase #4 $243.29   10.194%   $268.091   $268.09   $268.10   $268.10  
  Purchase #5 $185.92   6.819%   $198.5979   $198.60   $198.60   $198.60  
  Purchase #6 $159.48   3.126%   $164.4653   $164.47   $164.45   $164.50  
  Purchase #7 $113.49   3.542%   $117.5098   $117.51   $117.50   $117.50  
  7 purchase totals = $1,064.09       $1,134.4973   $1,134.51   $1,134.50   $1,134.50