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	$194.44	5.460%	$205.0564	$205.06	$205.05	$205.10
Purchase #2	$112.70	13.389%	$127.7894	$127.79	$127.80	$127.80
Purchase #3	$229.63	7.342%	$246.4894	$246.49	$246.50	$246.50
Purchase #4	$46.78	11.265%	$52.0498	$52.05	$52.05	$52.00
Purchase #5	$25.60	10.407%	$28.2642	$28.26	$28.25	$28.30
Purchase #6	$135.86	6.842%	$145.1555	$145.16	$145.15	$145.20
Purchase #7	$189.76	3.690%	$196.7621	$196.76	$196.75	$196.80
7 purchase totals =	$934.77		$1,001.5668	$1,001.57	$1,001.55	$1,001.70