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	$213.94	7.665%	$230.3385	$230.34	$230.35	$230.30
Purchase #2	$159.68	5.478%	$168.4273	$168.43	$168.45	$168.40
Purchase #3	$43.25	4.103%	$45.0245	$45.02	$45.00	$45.00
Purchase #4	$124.90	11.344%	$139.0687	$139.07	$139.05	$139.10
Purchase #5	$238.61	13.475%	$270.7627	$270.76	$270.75	$270.80
Purchase #6	$132.53	13.722%	$150.7158	$150.72	$150.70	$150.70
Purchase #7	$96.60	13.639%	$109.7753	$109.78	$109.80	$109.80
7 purchase totals =	$1,009.51		$1,114.1128	$1,114.12	$1,114.10	$1,114.10