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	$208.51	10.667%	$230.7518	$230.75	$230.75	$230.80
Purchase #2	$163.72	7.283%	$175.6437	$175.64	$175.65	$175.60
Purchase #3	$180.48	7.819%	$194.5917	$194.59	$194.60	$194.60
Purchase #4	$206.78	10.432%	$228.3513	$228.35	$228.35	$228.40
Purchase #5	$28.51	10.210%	$31.4209	$31.42	$31.40	$31.40
Purchase #6	$133.57	4.232%	$139.2227	$139.22	$139.20	$139.20
Purchase #7	$53.33	11.575%	$59.5029	$59.50	$59.50	$59.50
7 purchase totals =	$974.90		$1,059.4850	$1,059.47	$1,059.45	$1,059.50