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	$147.38	8.872%	$160.4556	$160.46	$160.45	$160.50
Purchase #2	$19.86	4.329%	$20.7197	$20.72	$20.70	$20.70
Purchase #3	$85.49	4.290%	$89.1575	$89.16	$89.15	$89.20
Purchase #4	$59.77	13.493%	$67.8348	$67.83	$67.85	$67.80
Purchase #5	$68.63	11.864%	$76.7723	$76.77	$76.75	$76.80
Purchase #6	$214.88	10.673%	$237.8141	$237.81	$237.80	$237.80
Purchase #7	$224.31	13.411%	$254.3922	$254.39	$254.40	$254.40
7 purchase totals =	$820.32		$907.1462	$907.14	$907.10	$907.20