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	$154.85	4.728%	$162.1713	$162.17	$162.15	$162.20
Purchase #2	$196.29	12.723%	$221.264	$221.26	$221.25	$221.30
Purchase #3	$28.82	13.179%	$32.6182	$32.62	$32.60	$32.60
Purchase #4	$205.85	3.184%	$212.4043	$212.40	$212.40	$212.40
Purchase #5	$48.48	10.263%	$53.4555	$53.46	$53.45	$53.50
Purchase #6	$174.50	10.560%	$192.9272	$192.93	$192.95	$192.90
Purchase #7	$150.65	6.627%	$160.6336	$160.63	$160.65	$160.60
7 purchase totals =	$959.44		$1,035.4741	$1,035.47	$1,035.45	$1,035.50