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	$211.93	11.482%	$236.2638	$236.26	$236.25	$236.30
Purchase #2	$210.46	13.167%	$238.1713	$238.17	$238.15	$238.20
Purchase #3	$225.58	5.745%	$238.5396	$238.54	$238.55	$238.50
Purchase #4	$153.91	10.410%	$169.932	$169.93	$169.95	$169.90
Purchase #5	$148.87	5.181%	$156.583	$156.58	$156.60	$156.60
Purchase #6	$222.95	10.154%	$245.5883	$245.59	$245.60	$245.60
Purchase #7	$102.75	8.345%	$111.3245	$111.32	$111.30	$111.30
7 purchase totals =	$1,276.45		$1,396.4025	$1,396.39	$1,396.40	$1,396.40