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	$116.59	9.500%	$127.6661	$127.67	$127.65	$127.70
Purchase #2	$47.62	13.825%	$54.2035	$54.20	$54.20	$54.20
Purchase #3	$142.29	7.793%	$153.3787	$153.38	$153.40	$153.40
Purchase #4	$200.62	4.240%	$209.1263	$209.13	$209.15	$209.10
Purchase #5	$202.32	13.577%	$229.789	$229.79	$229.80	$229.80
Purchase #6	$143.29	4.146%	$149.2308	$149.23	$149.25	$149.20
Purchase #7	$131.55	8.347%	$142.5305	$142.53	$142.55	$142.50
7 purchase totals =	$984.28		$1,065.9249	$1,065.93	$1,066.00	$1,065.90