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	$60.43	3.734%	$62.6865	$62.69	$62.70	$62.70
Purchase #2	$52.27	13.746%	$59.455	$59.46	$59.45	$59.50
Purchase #3	$245.38	11.734%	$274.1729	$274.17	$274.15	$274.20
Purchase #4	$142.88	13.386%	$162.0059	$162.01	$162.00	$162.00
Purchase #5	$163.39	4.697%	$171.0644	$171.06	$171.05	$171.10
Purchase #6	$154.87	5.521%	$163.4204	$163.42	$163.40	$163.40
Purchase #7	$135.88	7.742%	$146.3998	$146.40	$146.40	$146.40
7 purchase totals =	$955.10		$1,039.2049	$1,039.21	$1,039.15	$1,039.30