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	$106.78	5.845%	$113.0213	$113.02	$113.00	$113.00
Purchase #2	$194.86	5.493%	$205.5637	$205.56	$205.55	$205.60
Purchase #3	$208.55	6.699%	$222.5208	$222.52	$222.50	$222.50
Purchase #4	$164.71	12.140%	$184.7058	$184.71	$184.70	$184.70
Purchase #5	$201.46	13.251%	$228.1555	$228.16	$228.15	$228.20
Purchase #6	$52.53	6.271%	$55.8242	$55.82	$55.80	$55.80
Purchase #7	$156.50	6.524%	$166.7101	$166.71	$166.70	$166.70
7 purchase totals =	$1,085.39		$1,176.5014	$1,176.50	$1,176.40	$1,176.50