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	$161.94	3.505%	$167.616	$167.62	$167.60	$167.60
Purchase #2	$55.71	3.606%	$57.7189	$57.72	$57.70	$57.70
Purchase #3	$247.30	6.485%	$263.3374	$263.34	$263.35	$263.30
Purchase #4	$213.53	13.277%	$241.8804	$241.88	$241.90	$241.90
Purchase #5	$141.85	11.714%	$158.4663	$158.47	$158.45	$158.50
Purchase #6	$228.56	10.218%	$251.9143	$251.91	$251.90	$251.90
Purchase #7	$117.33	8.561%	$127.3746	$127.37	$127.35	$127.40
7 purchase totals =	$1,166.22		$1,268.3079	$1,268.31	$1,268.25	$1,268.30