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	$152.83	7.497%	$164.2877	$164.29	$164.30	$164.30
Purchase #2	$194.64	7.179%	$208.6132	$208.61	$208.60	$208.60
Purchase #3	$49.39	9.780%	$54.2203	$54.22	$54.20	$54.20
Purchase #4	$58.35	8.353%	$63.224	$63.22	$63.20	$63.20
Purchase #5	$92.96	13.448%	$105.4613	$105.46	$105.45	$105.50
Purchase #6	$240.50	5.663%	$254.1195	$254.12	$254.10	$254.10
Purchase #7	$33.70	3.803%	$34.9816	$34.98	$35.00	$35.00
7 purchase totals =	$822.37		$884.9076	$884.90	$884.85	$884.90