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	$111.55	10.589%	$123.362	$123.36	$123.35	$123.40
Purchase #2	$30.30	9.587%	$33.2049	$33.20	$33.20	$33.20
Purchase #3	$230.75	3.344%	$238.4663	$238.47	$238.45	$238.50
Purchase #4	$202.55	3.317%	$209.2686	$209.27	$209.25	$209.30
Purchase #5	$12.63	8.112%	$13.6545	$13.65	$13.65	$13.70
Purchase #6	$231.90	5.318%	$244.2324	$244.23	$244.25	$244.20
Purchase #7	$100.65	4.567%	$105.2467	$105.25	$105.25	$105.20
7 purchase totals =	$920.33		$967.4354	$967.43	$967.40	$967.50