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	$222.84	8.218%	$241.153	$241.15	$241.15	$241.20
Purchase #2	$64.27	4.507%	$67.1666	$67.17	$67.15	$67.20
Purchase #3	$57.54	13.185%	$65.1266	$65.13	$65.15	$65.10
Purchase #4	$220.52	6.563%	$234.9927	$234.99	$235.00	$235.00
Purchase #5	$154.94	10.643%	$171.4303	$171.43	$171.45	$171.40
Purchase #6	$165.42	7.795%	$178.3145	$178.31	$178.30	$178.30
Purchase #7	$173.64	10.540%	$191.9417	$191.94	$191.95	$191.90
7 purchase totals =	$1,059.17		$1,150.1254	$1,150.12	$1,150.15	$1,150.10