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	$164.89	5.497%	$173.954	$173.95	$173.95	$174.00
Purchase #2	$170.72	13.789%	$194.2606	$194.26	$194.25	$194.30
Purchase #3	$25.60	7.170%	$27.4355	$27.44	$27.45	$27.40
Purchase #4	$167.73	10.381%	$185.1421	$185.14	$185.15	$185.10
Purchase #5	$114.90	12.120%	$128.8259	$128.83	$128.85	$128.80
Purchase #6	$100.99	3.514%	$104.5388	$104.54	$104.55	$104.50
Purchase #7	$238.51	13.856%	$271.5579	$271.56	$271.55	$271.60
7 purchase totals =	$983.34		$1,085.7148	$1,085.72	$1,085.75	$1,085.70