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	$224.51	10.479%	$248.0364	$248.04	$248.05	$248.00
Purchase #2	$73.92	3.487%	$76.4976	$76.50	$76.50	$76.50
Purchase #3	$159.89	3.579%	$165.6125	$165.61	$165.60	$165.60
Purchase #4	$126.41	13.593%	$143.5929	$143.59	$143.60	$143.60
Purchase #5	$174.27	3.721%	$180.7546	$180.75	$180.75	$180.80
Purchase #6	$105.61	10.666%	$116.8744	$116.87	$116.85	$116.90
Purchase #7	$157.92	5.352%	$166.3719	$166.37	$166.35	$166.40
7 purchase totals =	$1,022.53		$1,097.7403	$1,097.73	$1,097.70	$1,097.80