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	$71.66	6.144%	$76.0628	$76.06	$76.05	$76.10
Purchase #2	$48.67	10.142%	$53.6061	$53.61	$53.60	$53.60
Purchase #3	$154.52	12.558%	$173.9246	$173.92	$173.90	$173.90
Purchase #4	$194.69	11.544%	$217.165	$217.17	$217.15	$217.20
Purchase #5	$186.30	5.497%	$196.5409	$196.54	$196.55	$196.50
Purchase #6	$201.48	12.468%	$226.6005	$226.60	$226.60	$226.60
Purchase #7	$62.70	3.229%	$64.7246	$64.72	$64.70	$64.70
7 purchase totals =	$920.02		$1,008.6245	$1,008.62	$1,008.55	$1,008.60