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	$224.47	13.369%	$254.4794	$254.48	$254.50	$254.50
Purchase #2	$187.99	13.441%	$213.2577	$213.26	$213.25	$213.30
Purchase #3	$48.89	13.579%	$55.5288	$55.53	$55.55	$55.50
Purchase #4	$128.36	8.583%	$139.3771	$139.38	$139.40	$139.40
Purchase #5	$122.83	6.537%	$130.8594	$130.86	$130.85	$130.90
Purchase #6	$122.96	3.378%	$127.1136	$127.11	$127.10	$127.10
Purchase #7	$176.42	4.198%	$183.8261	$183.83	$183.85	$183.80
7 purchase totals =	$1,011.92		$1,104.4421	$1,104.45	$1,104.50	$1,104.50