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	$84.50	13.242%	$95.6895	$95.69	$95.70	$95.70
Purchase #2	$136.97	10.526%	$151.3875	$151.39	$151.40	$151.40
Purchase #3	$78.66	13.358%	$89.1674	$89.17	$89.15	$89.20
Purchase #4	$111.41	5.238%	$117.2457	$117.25	$117.25	$117.20
Purchase #5	$46.91	12.627%	$52.8333	$52.83	$52.85	$52.80
Purchase #6	$27.28	7.336%	$29.2813	$29.28	$29.30	$29.30
Purchase #7	$180.38	4.469%	$188.4412	$188.44	$188.45	$188.40
7 purchase totals =	$666.11		$724.0459	$724.05	$724.10	$724.00