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	$205.26	4.387%	$214.2648	$214.26	$214.25	$214.30
Purchase #2	$69.27	13.415%	$78.5626	$78.56	$78.55	$78.60
Purchase #3	$119.81	11.388%	$133.454	$133.45	$133.45	$133.50
Purchase #4	$233.61	9.112%	$254.8965	$254.90	$254.90	$254.90
Purchase #5	$147.82	8.657%	$160.6168	$160.62	$160.60	$160.60
Purchase #6	$209.85	4.636%	$219.5786	$219.58	$219.60	$219.60
Purchase #7	$10.42	8.342%	$11.2892	$11.29	$11.30	$11.30
7 purchase totals =	$996.04		$1,072.6625	$1,072.66	$1,072.65	$1,072.80