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	$244.48	7.593%	$263.0434	$263.04	$263.05	$263.00
Purchase #2	$106.87	12.527%	$120.2576	$120.26	$120.25	$120.30
Purchase #3	$13.37	3.118%	$13.7869	$13.79	$13.80	$13.80
Purchase #4	$133.78	8.597%	$145.2811	$145.28	$145.30	$145.30
Purchase #5	$161.91	3.384%	$167.389	$167.39	$167.40	$167.40
Purchase #6	$199.78	11.821%	$223.396	$223.40	$223.40	$223.40
Purchase #7	$91.50	9.375%	$100.0781	$100.08	$100.10	$100.10
7 purchase totals =	$951.69		$1,033.2321	$1,033.24	$1,033.30	$1,033.30