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	$214.33	13.454%	$243.166	$243.17	$243.15	$243.20
Purchase #2	$7.94	7.252%	$8.5158	$8.52	$8.50	$8.50
Purchase #3	$184.83	6.244%	$196.3708	$196.37	$196.35	$196.40
Purchase #4	$240.37	11.517%	$268.0534	$268.05	$268.05	$268.10
Purchase #5	$115.46	10.571%	$127.6653	$127.67	$127.65	$127.70
Purchase #6	$229.55	13.278%	$260.0296	$260.03	$260.05	$260.00
Purchase #7	$90.75	5.142%	$95.4164	$95.42	$95.40	$95.40
7 purchase totals =	$1,083.23		$1,199.2173	$1,199.23	$1,199.15	$1,199.30