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	$145.98	11.295%	$162.4684	$162.47	$162.45	$162.50
Purchase #2	$190.96	12.439%	$214.7135	$214.71	$214.70	$214.70
Purchase #3	$33.60	11.504%	$37.4653	$37.47	$37.45	$37.50
Purchase #4	$158.49	5.832%	$167.7331	$167.73	$167.75	$167.70
Purchase #5	$28.78	12.380%	$32.343	$32.34	$32.35	$32.30
Purchase #6	$130.47	10.125%	$143.6801	$143.68	$143.70	$143.70
Purchase #7	$239.75	3.364%	$247.8152	$247.82	$247.80	$247.80
7 purchase totals =	$928.03		$1,006.2186	$1,006.22	$1,006.20	$1,006.20