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	$185.49	5.706%	$196.0741	$196.07	$196.05	$196.10
Purchase #2	$228.55	4.605%	$239.0747	$239.07	$239.05	$239.10
Purchase #3	$175.41	5.551%	$185.147	$185.15	$185.15	$185.10
Purchase #4	$133.77	4.217%	$139.4111	$139.41	$139.40	$139.40
Purchase #5	$155.61	13.517%	$176.6438	$176.64	$176.65	$176.60
Purchase #6	$188.60	12.659%	$212.4749	$212.47	$212.45	$212.50
Purchase #7	$28.62	10.688%	$31.6789	$31.68	$31.70	$31.70
7 purchase totals =	$1,096.05		$1,180.5045	$1,180.49	$1,180.45	$1,180.50