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	$147.68	3.174%	$152.3674	$152.37	$152.35	$152.40
Purchase #2	$156.25	10.488%	$172.6375	$172.64	$172.65	$172.60
Purchase #3	$99.99	11.551%	$111.5398	$111.54	$111.55	$111.50
Purchase #4	$122.73	12.847%	$138.4971	$138.50	$138.50	$138.50
Purchase #5	$89.27	12.209%	$100.169	$100.17	$100.15	$100.20
Purchase #6	$246.87	7.525%	$265.447	$265.45	$265.45	$265.40
Purchase #7	$244.79	9.679%	$268.4832	$268.48	$268.50	$268.50
7 purchase totals =	$1,107.58		$1,209.1410	$1,209.15	$1,209.15	$1,209.10