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	$220.43	4.619%	$230.6117	$230.61	$230.60	$230.60
Purchase #2	$88.91	6.709%	$94.875	$94.88	$94.90	$94.90
Purchase #3	$226.64	9.199%	$247.4886	$247.49	$247.50	$247.50
Purchase #4	$99.32	5.194%	$104.4787	$104.48	$104.50	$104.50
Purchase #5	$241.89	4.234%	$252.1316	$252.13	$252.15	$252.10
Purchase #6	$73.63	10.599%	$81.434	$81.43	$81.45	$81.40
Purchase #7	$82.60	4.705%	$86.4863	$86.49	$86.50	$86.50
7 purchase totals =	$1,033.42		$1,097.5059	$1,097.51	$1,097.60	$1,097.50