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	$139.30	10.275%	$153.6131	$153.61	$153.60	$153.60
Purchase #2	$249.58	10.689%	$276.2576	$276.26	$276.25	$276.30
Purchase #3	$108.29	13.727%	$123.155	$123.16	$123.15	$123.20
Purchase #4	$238.40	6.312%	$253.4478	$253.45	$253.45	$253.40
Purchase #5	$38.30	5.717%	$40.4896	$40.49	$40.50	$40.50
Purchase #6	$150.72	4.866%	$158.054	$158.05	$158.05	$158.10
Purchase #7	$142.36	3.179%	$146.8856	$146.89	$146.90	$146.90
7 purchase totals =	$1,066.95		$1,151.9027	$1,151.91	$1,151.90	$1,152.00