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	$223.47	6.783%	$238.628	$238.63	$238.65	$238.60
Purchase #2	$212.59	3.843%	$220.7598	$220.76	$220.75	$220.80
Purchase #3	$159.78	9.634%	$175.1732	$175.17	$175.15	$175.20
Purchase #4	$69.78	3.863%	$72.4756	$72.48	$72.50	$72.50
Purchase #5	$111.79	4.312%	$116.6104	$116.61	$116.60	$116.60
Purchase #6	$32.53	5.194%	$34.2196	$34.22	$34.20	$34.20
Purchase #7	$179.89	13.253%	$203.7308	$203.73	$203.75	$203.70
7 purchase totals =	$989.83		$1,061.5974	$1,061.60	$1,061.60	$1,061.60