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	$175.48	10.328%	$193.6036	$193.60	$193.60	$193.60
Purchase #2	$170.47	3.280%	$176.0614	$176.06	$176.05	$176.10
Purchase #3	$208.49	4.119%	$217.0777	$217.08	$217.10	$217.10
Purchase #4	$147.41	7.706%	$158.7694	$158.77	$158.75	$158.80
Purchase #5	$155.75	10.707%	$172.4262	$172.43	$172.45	$172.40
Purchase #6	$66.76	7.123%	$71.5153	$71.52	$71.50	$71.50
Purchase #7	$141.44	10.263%	$155.956	$155.96	$155.95	$156.00
7 purchase totals =	$1,065.80		$1,145.4096	$1,145.42	$1,145.40	$1,145.50