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	$151.43	4.637%	$158.4518	$158.45	$158.45	$158.50
Purchase #2	$96.63	9.633%	$105.9384	$105.94	$105.95	$105.90
Purchase #3	$187.99	6.540%	$200.2845	$200.28	$200.30	$200.30
Purchase #4	$157.46	13.375%	$178.5203	$178.52	$178.50	$178.50
Purchase #5	$111.62	13.260%	$126.4208	$126.42	$126.40	$126.40
Purchase #6	$70.43	4.811%	$73.8184	$73.82	$73.80	$73.80
Purchase #7	$167.61	8.448%	$181.7697	$181.77	$181.75	$181.80
7 purchase totals =	$943.17		$1,025.2039	$1,025.20	$1,025.15	$1,025.20