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	$193.93	11.370%	$215.9798	$215.98	$216.00	$216.00
Purchase #2	$34.69	6.305%	$36.8772	$36.88	$36.90	$36.90
Purchase #3	$243.74	9.821%	$267.6777	$267.68	$267.70	$267.70
Purchase #4	$117.25	13.320%	$132.8677	$132.87	$132.85	$132.90
Purchase #5	$168.49	13.849%	$191.8242	$191.82	$191.80	$191.80
Purchase #6	$103.71	7.469%	$111.4561	$111.46	$111.45	$111.50
Purchase #7	$142.46	11.207%	$158.4255	$158.43	$158.45	$158.40
7 purchase totals =	$1,004.27		$1,115.1082	$1,115.12	$1,115.15	$1,115.20