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	$102.65	8.368%	$111.2398	$111.24	$111.25	$111.20
Purchase #2	$80.84	7.533%	$86.9297	$86.93	$86.95	$86.90
Purchase #3	$231.44	4.621%	$242.1348	$242.13	$242.15	$242.10
Purchase #4	$96.42	3.274%	$99.5768	$99.58	$99.60	$99.60
Purchase #5	$236.69	11.133%	$263.0407	$263.04	$263.05	$263.00
Purchase #6	$198.83	5.836%	$210.4337	$210.43	$210.45	$210.40
Purchase #7	$77.41	8.186%	$83.7468	$83.75	$83.75	$83.70
7 purchase totals =	$1,024.28		$1,097.1023	$1,097.10	$1,097.20	$1,096.90