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	$58.34	6.194%	$61.9536	$61.95	$61.95	$62.00
Purchase #2	$173.88	8.372%	$188.4372	$188.44	$188.45	$188.40
Purchase #3	$246.97	13.746%	$280.9185	$280.92	$280.90	$280.90
Purchase #4	$237.69	13.664%	$270.168	$270.17	$270.15	$270.20
Purchase #5	$58.29	13.447%	$66.1283	$66.13	$66.15	$66.10
Purchase #6	$100.94	10.455%	$111.4933	$111.49	$111.50	$111.50
Purchase #7	$120.68	5.583%	$127.4176	$127.42	$127.40	$127.40
7 purchase totals =	$996.79		$1,106.5165	$1,106.52	$1,106.50	$1,106.50