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	$104.78	13.726%	$119.1621	$119.16	$119.15	$119.20
Purchase #2	$119.54	6.739%	$127.5958	$127.60	$127.60	$127.60
Purchase #3	$52.46	7.539%	$56.415	$56.42	$56.40	$56.40
Purchase #4	$94.26	5.555%	$99.4961	$99.50	$99.50	$99.50
Purchase #5	$221.30	3.871%	$229.8665	$229.87	$229.85	$229.90
Purchase #6	$163.51	5.150%	$171.9308	$171.93	$171.95	$171.90
Purchase #7	$118.97	9.662%	$130.4649	$130.46	$130.45	$130.50
7 purchase totals =	$874.82		$934.9312	$934.94	$934.90	$935.00