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	$89.66	5.801%	$94.8612	$94.86	$94.85	$94.90
Purchase #2	$88.43	11.827%	$98.8886	$98.89	$98.90	$98.90
Purchase #3	$158.82	7.446%	$170.6457	$170.65	$170.65	$170.60
Purchase #4	$101.75	10.656%	$112.5925	$112.59	$112.60	$112.60
Purchase #5	$216.67	6.232%	$230.1729	$230.17	$230.15	$230.20
Purchase #6	$178.56	4.120%	$185.9167	$185.92	$185.90	$185.90
Purchase #7	$134.78	3.483%	$139.4744	$139.47	$139.45	$139.50
7 purchase totals =	$968.67		$1,032.5520	$1,032.55	$1,032.50	$1,032.60