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	$92.84	4.803%	$97.2991	$97.30	$97.30	$97.30
Purchase #2	$127.76	4.848%	$133.9538	$133.95	$133.95	$134.00
Purchase #3	$89.76	12.443%	$100.9288	$100.93	$100.95	$100.90
Purchase #4	$138.38	6.575%	$147.4785	$147.48	$147.50	$147.50
Purchase #5	$175.78	9.152%	$191.8674	$191.87	$191.85	$191.90
Purchase #6	$177.96	6.812%	$190.0826	$190.08	$190.10	$190.10
Purchase #7	$188.69	12.603%	$212.4706	$212.47	$212.45	$212.50
7 purchase totals =	$991.17		$1,074.0808	$1,074.08	$1,074.10	$1,074.20