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	$117.89	8.248%	$127.6136	$127.61	$127.60	$127.60
Purchase #2	$232.89	4.449%	$243.2513	$243.25	$243.25	$243.30
Purchase #3	$18.58	13.789%	$21.142	$21.14	$21.15	$21.10
Purchase #4	$167.54	13.562%	$190.2618	$190.26	$190.25	$190.30
Purchase #5	$7.38	13.533%	$8.3787	$8.38	$8.40	$8.40
Purchase #6	$241.35	5.335%	$254.226	$254.23	$254.25	$254.20
Purchase #7	$178.28	7.751%	$192.0985	$192.10	$192.10	$192.10
7 purchase totals =	$963.91		$1,036.9719	$1,036.97	$1,037.00	$1,037.00