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	$165.95	9.414%	$181.5725	$181.57	$181.55	$181.60
Purchase #2	$214.46	7.820%	$231.2308	$231.23	$231.25	$231.20
Purchase #3	$88.47	7.813%	$95.3822	$95.38	$95.40	$95.40
Purchase #4	$120.65	9.818%	$132.4954	$132.50	$132.50	$132.50
Purchase #5	$75.61	3.698%	$78.4061	$78.41	$78.40	$78.40
Purchase #6	$241.52	11.629%	$269.6064	$269.61	$269.60	$269.60
Purchase #7	$52.52	12.818%	$59.252	$59.25	$59.25	$59.30
7 purchase totals =	$959.18		$1,047.9454	$1,047.95	$1,047.95	$1,048.00