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	$211.58	10.861%	$234.5597	$234.56	$234.55	$234.60
Purchase #2	$216.51	6.377%	$230.3168	$230.32	$230.30	$230.30
Purchase #3	$66.84	5.631%	$70.6038	$70.60	$70.60	$70.60
Purchase #4	$66.30	8.487%	$71.9269	$71.93	$71.95	$71.90
Purchase #5	$76.52	7.492%	$82.2529	$82.25	$82.25	$82.30
Purchase #6	$177.72	7.729%	$191.456	$191.46	$191.45	$191.50
Purchase #7	$182.67	3.671%	$189.3758	$189.38	$189.40	$189.40
7 purchase totals =	$998.14		$1,070.4919	$1,070.50	$1,070.50	$1,070.60