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	$219.92	3.157%	$226.8629	$226.86	$226.85	$226.90
Purchase #2	$164.68	4.522%	$172.1268	$172.13	$172.15	$172.10
Purchase #3	$226.40	5.228%	$238.2362	$238.24	$238.25	$238.20
Purchase #4	$178.57	4.242%	$186.1449	$186.14	$186.15	$186.10
Purchase #5	$217.61	7.280%	$233.452	$233.45	$233.45	$233.50
Purchase #6	$221.27	3.788%	$229.6517	$229.65	$229.65	$229.70
Purchase #7	$104.41	6.356%	$111.0463	$111.05	$111.05	$111.00
7 purchase totals =	$1,332.86		$1,397.5208	$1,397.52	$1,397.55	$1,397.50