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	$208.85	10.103%	$229.9501	$229.95	$229.95	$230.00
Purchase #2	$35.40	3.348%	$36.5852	$36.59	$36.60	$36.60
Purchase #3	$176.27	9.428%	$192.8887	$192.89	$192.90	$192.90
Purchase #4	$93.32	6.798%	$99.6639	$99.66	$99.65	$99.70
Purchase #5	$189.56	7.574%	$203.9173	$203.92	$203.90	$203.90
Purchase #6	$118.94	7.467%	$127.8212	$127.82	$127.80	$127.80
Purchase #7	$110.86	13.834%	$126.1964	$126.20	$126.20	$126.20
7 purchase totals =	$933.20		$1,017.0228	$1,017.03	$1,017.00	$1,017.10