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	$162.31	7.742%	$174.876	$174.88	$174.90	$174.90
Purchase #2	$16.95	11.380%	$18.8789	$18.88	$18.90	$18.90
Purchase #3	$10.80	12.189%	$12.1164	$12.12	$12.10	$12.10
Purchase #4	$50.68	13.637%	$57.5912	$57.59	$57.60	$57.60
Purchase #5	$167.49	5.393%	$176.5227	$176.52	$176.50	$176.50
Purchase #6	$81.45	8.599%	$88.4539	$88.45	$88.45	$88.50
Purchase #7	$223.85	9.477%	$245.0643	$245.06	$245.05	$245.10
7 purchase totals =	$713.53		$773.5034	$773.50	$773.50	$773.60