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	$147.40	4.382%	$153.8591	$153.86	$153.85	$153.90
Purchase #2	$39.56	5.732%	$41.8276	$41.83	$41.85	$41.80
Purchase #3	$83.69	7.615%	$90.063	$90.06	$90.05	$90.10
Purchase #4	$196.62	12.778%	$221.7441	$221.74	$221.75	$221.70
Purchase #5	$107.39	3.298%	$110.9317	$110.93	$110.95	$110.90
Purchase #6	$131.38	12.351%	$147.6067	$147.61	$147.60	$147.60
Purchase #7	$246.84	6.216%	$262.1836	$262.18	$262.20	$262.20
7 purchase totals =	$952.88		$1,028.2158	$1,028.21	$1,028.25	$1,028.20