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	$142.28	4.244%	$148.3184	$148.32	$148.30	$148.30
Purchase #2	$10.41	11.711%	$11.6291	$11.63	$11.65	$11.60
Purchase #3	$95.43	7.501%	$102.5882	$102.59	$102.60	$102.60
Purchase #4	$183.68	5.167%	$193.1707	$193.17	$193.15	$193.20
Purchase #5	$58.83	12.700%	$66.3014	$66.30	$66.30	$66.30
Purchase #6	$176.96	7.700%	$190.5859	$190.59	$190.60	$190.60
Purchase #7	$200.80	5.807%	$212.4605	$212.46	$212.45	$212.50
7 purchase totals =	$868.39		$925.0542	$925.06	$925.05	$925.10