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	$147.52	4.172%	$153.6745	$153.67	$153.65	$153.70
Purchase #2	$125.78	12.542%	$141.5553	$141.56	$141.55	$141.60
Purchase #3	$65.28	3.579%	$67.6164	$67.62	$67.60	$67.60
Purchase #4	$136.78	11.759%	$152.864	$152.86	$152.85	$152.90
Purchase #5	$119.72	5.320%	$126.0891	$126.09	$126.10	$126.10
Purchase #6	$119.72	6.486%	$127.485	$127.49	$127.50	$127.50
Purchase #7	$43.41	7.495%	$46.6636	$46.66	$46.65	$46.70
7 purchase totals =	$758.21		$815.9479	$815.95	$815.90	$816.10