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 $94.67   7.584%   $101.8498   $101.85   $101.85   $101.80  
  Purchase #2 $46.68   4.259%   $48.6681   $48.67   $48.65   $48.70  
  Purchase #3 $185.69   5.227%   $195.396   $195.40   $195.40   $195.40  
  Purchase #4 $98.99   9.762%   $108.6534   $108.65   $108.65   $108.70  
  Purchase #5 $148.90   3.205%   $153.6722   $153.67   $153.65   $153.70  
  Purchase #6 $165.81   11.658%   $185.1401   $185.14   $185.15   $185.10  
  Purchase #7 $245.82   8.706%   $267.2211   $267.22   $267.20   $267.20  
  7 purchase totals = $986.56       $1,060.6007   $1,060.60   $1,060.55   $1,060.60