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	$250.28	4.795%	$262.2809	$262.28	$262.30	$262.30
Purchase #2	$211.93	6.555%	$225.822	$225.82	$225.80	$225.80
Purchase #3	$100.74	10.565%	$111.3832	$111.38	$111.40	$111.40
Purchase #4	$159.78	8.730%	$173.7288	$173.73	$173.75	$173.70
Purchase #5	$185.42	3.299%	$191.537	$191.54	$191.55	$191.50
Purchase #6	$7.32	4.407%	$7.6426	$7.64	$7.65	$7.60
Purchase #7	$174.43	4.195%	$181.7473	$181.75	$181.75	$181.70
7 purchase totals =	$1,089.90		$1,154.1418	$1,154.14	$1,154.20	$1,154.00