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	$33.41	4.805%	$35.0154	$35.02	$35.00	$35.00
Purchase #2	$80.50	10.728%	$89.136	$89.14	$89.15	$89.10
Purchase #3	$217.37	5.318%	$228.9297	$228.93	$228.95	$228.90
Purchase #4	$151.61	5.853%	$160.4837	$160.48	$160.50	$160.50
Purchase #5	$70.28	4.734%	$73.6071	$73.61	$73.60	$73.60
Purchase #6	$52.69	3.591%	$54.5821	$54.58	$54.60	$54.60
Purchase #7	$51.95	3.365%	$53.6981	$53.70	$53.70	$53.70
7 purchase totals =	$657.81		$695.4521	$695.46	$695.50	$695.40