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	$196.90	5.716%	$208.1548	$208.15	$208.15	$208.20
Purchase #2	$158.58	5.299%	$166.9832	$166.98	$167.00	$167.00
Purchase #3	$151.81	4.415%	$158.5124	$158.51	$158.50	$158.50
Purchase #4	$101.95	9.731%	$111.8708	$111.87	$111.85	$111.90
Purchase #5	$219.45	9.729%	$240.8003	$240.80	$240.80	$240.80
Purchase #6	$173.86	4.718%	$182.0627	$182.06	$182.05	$182.10
Purchase #7	$161.92	10.251%	$178.5184	$178.52	$178.50	$178.50
7 purchase totals =	$1,164.47		$1,246.9026	$1,246.89	$1,246.85	$1,247.00