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	$11.31	4.594%	$11.8296	$11.83	$11.85	$11.80
Purchase #2	$32.73	3.523%	$33.8831	$33.88	$33.90	$33.90
Purchase #3	$58.44	4.495%	$61.0669	$61.07	$61.05	$61.10
Purchase #4	$80.46	3.411%	$83.2045	$83.20	$83.20	$83.20
Purchase #5	$245.92	9.379%	$268.9848	$268.98	$269.00	$269.00
Purchase #6	$134.63	5.800%	$142.4385	$142.44	$142.45	$142.40
Purchase #7	$154.56	11.770%	$172.7517	$172.75	$172.75	$172.80
7 purchase totals =	$718.05		$774.1591	$774.15	$774.20	$774.20