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	$173.96	5.179%	$182.9694	$182.97	$182.95	$183.00
Purchase #2	$116.86	9.205%	$127.617	$127.62	$127.60	$127.60
Purchase #3	$81.71	13.726%	$92.9255	$92.93	$92.95	$92.90
Purchase #4	$198.48	11.816%	$221.9324	$221.93	$221.95	$221.90
Purchase #5	$35.25	6.278%	$37.463	$37.46	$37.45	$37.50
Purchase #6	$149.41	9.595%	$163.7459	$163.75	$163.75	$163.70
Purchase #7	$172.89	11.409%	$192.615	$192.62	$192.60	$192.60
7 purchase totals =	$928.56		$1,019.2682	$1,019.28	$1,019.25	$1,019.20