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	$65.52	10.436%	$72.3577	$72.36	$72.35	$72.40
Purchase #2	$144.75	5.194%	$152.2683	$152.27	$152.25	$152.30
Purchase #3	$230.41	6.273%	$244.8636	$244.86	$244.85	$244.90
Purchase #4	$139.39	8.752%	$151.5894	$151.59	$151.60	$151.60
Purchase #5	$176.84	5.642%	$186.8173	$186.82	$186.80	$186.80
Purchase #6	$219.27	4.495%	$229.1262	$229.13	$229.15	$229.10
Purchase #7	$48.70	3.408%	$50.3597	$50.36	$50.35	$50.40
7 purchase totals =	$1,024.88		$1,087.3822	$1,087.39	$1,087.35	$1,087.50