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	$220.30	4.747%	$230.7576	$230.76	$230.75	$230.80
Purchase #2	$41.60	4.799%	$43.5964	$43.60	$43.60	$43.60
Purchase #3	$173.54	13.209%	$196.4629	$196.46	$196.45	$196.50
Purchase #4	$184.67	4.770%	$193.4788	$193.48	$193.50	$193.50
Purchase #5	$155.65	6.193%	$165.2894	$165.29	$165.30	$165.30
Purchase #6	$249.47	8.856%	$271.5631	$271.56	$271.55	$271.60
Purchase #7	$39.46	10.682%	$43.6751	$43.68	$43.70	$43.70
7 purchase totals =	$1,064.69		$1,144.8233	$1,144.83	$1,144.85	$1,145.00