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	$182.49	10.805%	$202.208	$202.21	$202.20	$202.20
Purchase #2	$157.64	10.536%	$174.249	$174.25	$174.25	$174.20
Purchase #3	$175.88	7.340%	$188.7896	$188.79	$188.80	$188.80
Purchase #4	$117.55	8.389%	$127.4113	$127.41	$127.40	$127.40
Purchase #5	$78.53	4.625%	$82.162	$82.16	$82.15	$82.20
Purchase #6	$56.33	9.222%	$61.5248	$61.52	$61.50	$61.50
Purchase #7	$215.25	8.457%	$233.4537	$233.45	$233.45	$233.50
7 purchase totals =	$983.67		$1,069.7984	$1,069.79	$1,069.75	$1,069.80