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	$103.99	7.649%	$111.9442	$111.94	$111.95	$111.90
Purchase #2	$214.64	6.438%	$228.4585	$228.46	$228.45	$228.50
Purchase #3	$104.81	12.786%	$118.211	$118.21	$118.20	$118.20
Purchase #4	$130.35	11.580%	$145.4445	$145.44	$145.45	$145.40
Purchase #5	$116.43	4.442%	$121.6018	$121.60	$121.60	$121.60
Purchase #6	$173.71	13.240%	$196.7092	$196.71	$196.70	$196.70
Purchase #7	$116.64	6.833%	$124.61	$124.61	$124.60	$124.60
7 purchase totals =	$960.57		$1,046.9792	$1,046.97	$1,046.95	$1,046.90