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	$145.64	3.451%	$150.666	$150.67	$150.65	$150.70
Purchase #2	$212.38	9.773%	$233.1359	$233.14	$233.15	$233.10
Purchase #3	$120.84	4.493%	$126.2693	$126.27	$126.25	$126.30
Purchase #4	$173.74	3.447%	$179.7288	$179.73	$179.75	$179.70
Purchase #5	$34.52	8.758%	$37.5433	$37.54	$37.55	$37.50
Purchase #6	$43.84	3.337%	$45.3029	$45.30	$45.30	$45.30
Purchase #7	$242.87	10.822%	$269.1534	$269.15	$269.15	$269.20
7 purchase totals =	$973.83		$1,041.7996	$1,041.80	$1,041.80	$1,041.80