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	$136.69	10.816%	$151.4744	$151.47	$151.45	$151.50
Purchase #2	$20.29	13.104%	$22.9488	$22.95	$22.95	$22.90
Purchase #3	$144.76	4.188%	$150.8225	$150.82	$150.80	$150.80
Purchase #4	$163.72	7.685%	$176.3019	$176.30	$176.30	$176.30
Purchase #5	$157.51	11.204%	$175.1574	$175.16	$175.15	$175.20
Purchase #6	$96.72	3.159%	$99.7754	$99.78	$99.80	$99.80
Purchase #7	$245.82	4.364%	$256.5476	$256.55	$256.55	$256.50
7 purchase totals =	$965.51		$1,033.0280	$1,033.03	$1,033.00	$1,033.00