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	$141.53	7.371%	$151.9622	$151.96	$151.95	$152.00
Purchase #2	$239.85	7.723%	$258.3736	$258.37	$258.35	$258.40
Purchase #3	$136.82	6.344%	$145.4999	$145.50	$145.50	$145.50
Purchase #4	$128.60	3.487%	$133.0843	$133.08	$133.10	$133.10
Purchase #5	$214.82	7.296%	$230.4933	$230.49	$230.50	$230.50
Purchase #6	$147.73	7.667%	$159.0565	$159.06	$159.05	$159.10
Purchase #7	$200.96	10.713%	$222.4888	$222.49	$222.50	$222.50
7 purchase totals =	$1,210.31		$1,300.9586	$1,300.95	$1,300.95	$1,301.10