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	$182.99	8.662%	$198.8406	$198.84	$198.85	$198.80
Purchase #2	$10.39	4.596%	$10.8675	$10.87	$10.85	$10.90
Purchase #3	$99.84	11.865%	$111.686	$111.69	$111.70	$111.70
Purchase #4	$43.69	10.397%	$48.2324	$48.23	$48.25	$48.20
Purchase #5	$149.64	10.126%	$164.7925	$164.79	$164.80	$164.80
Purchase #6	$221.53	10.414%	$244.6001	$244.60	$244.60	$244.60
Purchase #7	$216.70	5.414%	$228.4321	$228.43	$228.45	$228.40
7 purchase totals =	$924.78		$1,007.4512	$1,007.45	$1,007.50	$1,007.40