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	$141.29	4.388%	$147.4898	$147.49	$147.50	$147.50
Purchase #2	$191.63	10.342%	$211.4484	$211.45	$211.45	$211.40
Purchase #3	$218.56	5.563%	$230.7185	$230.72	$230.70	$230.70
Purchase #4	$173.72	4.699%	$181.8831	$181.88	$181.90	$181.90
Purchase #5	$123.58	3.717%	$128.1735	$128.17	$128.15	$128.20
Purchase #6	$150.53	3.307%	$155.508	$155.51	$155.50	$155.50
Purchase #7	$117.28	12.496%	$131.9353	$131.94	$131.95	$131.90
7 purchase totals =	$1,116.59		$1,187.1566	$1,187.16	$1,187.15	$1,187.10