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	$53.43	11.379%	$59.5098	$59.51	$59.50	$59.50
Purchase #2	$14.31	5.583%	$15.1089	$15.11	$15.10	$15.10
Purchase #3	$63.27	5.222%	$66.574	$66.57	$66.55	$66.60
Purchase #4	$19.83	11.326%	$22.0759	$22.08	$22.10	$22.10
Purchase #5	$206.25	5.158%	$216.8884	$216.89	$216.90	$216.90
Purchase #6	$173.99	6.139%	$184.6712	$184.67	$184.65	$184.70
Purchase #7	$175.83	5.518%	$185.5323	$185.53	$185.55	$185.50
7 purchase totals =	$706.91		$750.3605	$750.36	$750.35	$750.40