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	$107.77	6.231%	$114.4851	$114.49	$114.50	$114.50
Purchase #2	$13.45	3.555%	$13.9281	$13.93	$13.95	$13.90
Purchase #3	$168.69	12.316%	$189.4659	$189.47	$189.45	$189.50
Purchase #4	$102.76	8.745%	$111.7464	$111.75	$111.75	$111.70
Purchase #5	$155.62	9.187%	$169.9168	$169.92	$169.90	$169.90
Purchase #6	$224.68	5.180%	$236.3184	$236.32	$236.30	$236.30
Purchase #7	$220.98	13.202%	$250.1538	$250.15	$250.15	$250.20
7 purchase totals =	$993.95		$1,086.0145	$1,086.03	$1,086.00	$1,086.00