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	$82.63	13.248%	$93.5768	$93.58	$93.60	$93.60
Purchase #2	$66.89	8.137%	$72.3328	$72.33	$72.35	$72.30
Purchase #3	$27.35	7.525%	$29.4081	$29.41	$29.40	$29.40
Purchase #4	$226.87	5.121%	$238.488	$238.49	$238.50	$238.50
Purchase #5	$90.94	7.139%	$97.4322	$97.43	$97.45	$97.40
Purchase #6	$139.80	7.171%	$149.8251	$149.83	$149.85	$149.80
Purchase #7	$79.33	3.500%	$82.1066	$82.11	$82.10	$82.10
7 purchase totals =	$713.81		$763.1696	$763.18	$763.25	$763.10