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	$162.66	3.128%	$167.748	$167.75	$167.75	$167.70
Purchase #2	$139.54	13.346%	$158.163	$158.16	$158.15	$158.20
Purchase #3	$144.93	4.581%	$151.5692	$151.57	$151.55	$151.60
Purchase #4	$62.90	3.109%	$64.8556	$64.86	$64.85	$64.90
Purchase #5	$107.54	9.148%	$117.3778	$117.38	$117.40	$117.40
Purchase #6	$69.78	10.225%	$76.915	$76.92	$76.90	$76.90
Purchase #7	$34.37	10.665%	$38.0356	$38.04	$38.05	$38.00
7 purchase totals =	$721.72		$774.6642	$774.68	$774.65	$774.70