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	$250.89	7.197%	$268.9466	$268.95	$268.95	$268.90
Purchase #2	$145.53	7.461%	$156.388	$156.39	$156.40	$156.40
Purchase #3	$235.39	13.625%	$267.4619	$267.46	$267.45	$267.50
Purchase #4	$50.70	3.697%	$52.5744	$52.57	$52.55	$52.60
Purchase #5	$115.63	3.440%	$119.6077	$119.61	$119.60	$119.60
Purchase #6	$108.76	13.729%	$123.6917	$123.69	$123.70	$123.70
Purchase #7	$49.66	13.141%	$56.1858	$56.19	$56.20	$56.20
7 purchase totals =	$956.56		$1,044.8561	$1,044.86	$1,044.85	$1,044.90