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	$107.37	4.281%	$111.9665	$111.97	$111.95	$112.00
Purchase #2	$72.55	6.773%	$77.4638	$77.46	$77.45	$77.50
Purchase #3	$115.44	11.667%	$128.9084	$128.91	$128.90	$128.90
Purchase #4	$117.90	8.482%	$127.9003	$127.90	$127.90	$127.90
Purchase #5	$95.26	3.647%	$98.7341	$98.73	$98.75	$98.70
Purchase #6	$104.25	11.489%	$116.2273	$116.23	$116.25	$116.20
Purchase #7	$22.88	5.175%	$24.064	$24.06	$24.05	$24.10
7 purchase totals =	$635.65		$685.2644	$685.26	$685.25	$685.30