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	$190.88	5.282%	$200.9623	$200.96	$200.95	$201.00
Purchase #2	$240.38	13.277%	$272.2953	$272.30	$272.30	$272.30
Purchase #3	$211.81	8.674%	$230.1824	$230.18	$230.20	$230.20
Purchase #4	$85.33	4.451%	$89.128	$89.13	$89.15	$89.10
Purchase #5	$240.81	5.251%	$253.4549	$253.45	$253.45	$253.50
Purchase #6	$84.53	6.471%	$89.9999	$90.00	$90.00	$90.00
Purchase #7	$44.82	3.738%	$46.4954	$46.50	$46.50	$46.50
7 purchase totals =	$1,098.56		$1,182.5182	$1,182.52	$1,182.55	$1,182.60