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	$197.65	5.641%	$208.7994	$208.80	$208.80	$208.80
Purchase #2	$53.33	12.272%	$59.8747	$59.87	$59.85	$59.90
Purchase #3	$113.30	12.541%	$127.509	$127.51	$127.50	$127.50
Purchase #4	$226.54	11.449%	$252.4766	$252.48	$252.50	$252.50
Purchase #5	$40.61	13.621%	$46.1415	$46.14	$46.15	$46.10
Purchase #6	$11.37	3.586%	$11.7777	$11.78	$11.80	$11.80
Purchase #7	$111.34	7.398%	$119.5769	$119.58	$119.60	$119.60
7 purchase totals =	$754.14		$826.1558	$826.16	$826.20	$826.20