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	$107.32	6.245%	$114.0221	$114.02	$114.00	$114.00
Purchase #2	$57.29	4.193%	$59.6922	$59.69	$59.70	$59.70
Purchase #3	$179.39	9.283%	$196.0428	$196.04	$196.05	$196.00
Purchase #4	$172.92	11.738%	$193.2173	$193.22	$193.20	$193.20
Purchase #5	$31.88	8.193%	$34.4919	$34.49	$34.50	$34.50
Purchase #6	$35.72	6.702%	$38.114	$38.11	$38.10	$38.10
Purchase #7	$47.70	13.110%	$53.9535	$53.95	$53.95	$54.00
7 purchase totals =	$632.22		$689.5338	$689.52	$689.50	$689.50