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	$177.92	10.651%	$196.8703	$196.87	$196.85	$196.90
Purchase #2	$37.93	11.399%	$42.2536	$42.25	$42.25	$42.30
Purchase #3	$12.96	4.168%	$13.5002	$13.50	$13.50	$13.50
Purchase #4	$218.40	6.750%	$233.142	$233.14	$233.15	$233.10
Purchase #5	$141.54	4.596%	$148.0452	$148.05	$148.05	$148.00
Purchase #6	$229.53	9.608%	$251.5832	$251.58	$251.60	$251.60
Purchase #7	$220.26	4.868%	$230.9823	$230.98	$231.00	$231.00
7 purchase totals =	$1,038.54		$1,116.3768	$1,116.37	$1,116.40	$1,116.40