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	$153.83	7.864%	$165.9272	$165.93	$165.95	$165.90
Purchase #2	$57.61	3.213%	$59.461	$59.46	$59.45	$59.50
Purchase #3	$167.25	3.487%	$173.082	$173.08	$173.10	$173.10
Purchase #4	$44.96	9.774%	$49.3544	$49.35	$49.35	$49.40
Purchase #5	$244.59	5.314%	$257.5875	$257.59	$257.60	$257.60
Purchase #6	$67.77	9.770%	$74.3911	$74.39	$74.40	$74.40
Purchase #7	$215.69	13.308%	$244.394	$244.39	$244.40	$244.40
7 purchase totals =	$951.70		$1,024.1972	$1,024.19	$1,024.25	$1,024.30