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	$54.94	4.543%	$57.4359	$57.44	$57.45	$57.40
Purchase #2	$145.78	3.857%	$151.4027	$151.40	$151.40	$151.40
Purchase #3	$150.60	13.738%	$171.2894	$171.29	$171.30	$171.30
Purchase #4	$175.77	5.613%	$185.636	$185.64	$185.65	$185.60
Purchase #5	$56.87	5.258%	$59.8602	$59.86	$59.85	$59.90
Purchase #6	$230.62	5.379%	$243.025	$243.03	$243.05	$243.00
Purchase #7	$90.84	11.300%	$101.1049	$101.10	$101.10	$101.10
7 purchase totals =	$905.42		$969.7541	$969.76	$969.80	$969.70