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	$175.64	11.707%	$196.2022	$196.20	$196.20	$196.20
Purchase #2	$105.93	5.280%	$111.5231	$111.52	$111.50	$111.50
Purchase #3	$48.58	13.367%	$55.0737	$55.07	$55.05	$55.10
Purchase #4	$202.32	7.548%	$217.5911	$217.59	$217.60	$217.60
Purchase #5	$45.32	6.370%	$48.2069	$48.21	$48.20	$48.20
Purchase #6	$85.69	12.682%	$96.5572	$96.56	$96.55	$96.60
Purchase #7	$21.45	6.605%	$22.8668	$22.87	$22.85	$22.90
7 purchase totals =	$684.93		$748.0210	$748.02	$747.95	$748.10