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	$119.94	3.196%	$123.7733	$123.77	$123.75	$123.80
Purchase #2	$6.81	6.505%	$7.253	$7.25	$7.25	$7.30
Purchase #3	$101.43	10.353%	$111.931	$111.93	$111.95	$111.90
Purchase #4	$23.54	9.793%	$25.8453	$25.85	$25.85	$25.80
Purchase #5	$12.74	13.758%	$14.4928	$14.49	$14.50	$14.50
Purchase #6	$182.62	3.381%	$188.7944	$188.79	$188.80	$188.80
Purchase #7	$15.69	13.150%	$17.7532	$17.75	$17.75	$17.80
7 purchase totals =	$462.77		$489.8430	$489.83	$489.85	$489.90