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	$224.42	9.271%	$245.226	$245.23	$245.25	$245.20
Purchase #2	$122.65	4.277%	$127.8957	$127.90	$127.90	$127.90
Purchase #3	$189.73	9.661%	$208.0598	$208.06	$208.05	$208.10
Purchase #4	$61.72	9.350%	$67.4908	$67.49	$67.50	$67.50
Purchase #5	$105.48	5.731%	$111.5251	$111.53	$111.55	$111.50
Purchase #6	$230.49	9.705%	$252.8591	$252.86	$252.85	$252.90
Purchase #7	$82.61	11.370%	$92.0028	$92.00	$92.00	$92.00
7 purchase totals =	$1,017.10		$1,105.0593	$1,105.07	$1,105.10	$1,105.10