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	$209.36	11.462%	$233.3568	$233.36	$233.35	$233.40
Purchase #2	$55.35	12.799%	$62.4342	$62.43	$62.45	$62.40
Purchase #3	$229.43	11.351%	$255.4726	$255.47	$255.45	$255.50
Purchase #4	$143.76	8.709%	$156.2801	$156.28	$156.30	$156.30
Purchase #5	$228.86	3.663%	$237.2431	$237.24	$237.25	$237.20
Purchase #6	$227.38	11.481%	$253.4855	$253.49	$253.50	$253.50
Purchase #7	$210.64	8.141%	$227.7882	$227.79	$227.80	$227.80
7 purchase totals =	$1,304.78		$1,426.0605	$1,426.06	$1,426.10	$1,426.10