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	$173.40	13.406%	$196.646	$196.65	$196.65	$196.60
Purchase #2	$80.61	9.729%	$88.4525	$88.45	$88.45	$88.50
Purchase #3	$212.33	5.339%	$223.6663	$223.67	$223.65	$223.70
Purchase #4	$220.85	5.613%	$233.2463	$233.25	$233.25	$233.20
Purchase #5	$64.82	3.823%	$67.2981	$67.30	$67.30	$67.30
Purchase #6	$244.60	7.528%	$263.0135	$263.01	$263.00	$263.00
Purchase #7	$51.42	4.109%	$53.5328	$53.53	$53.55	$53.50
7 purchase totals =	$1,048.03		$1,125.8555	$1,125.86	$1,125.85	$1,125.80