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	$217.98	9.393%	$238.4549	$238.45	$238.45	$238.50
Purchase #2	$192.49	11.362%	$214.3607	$214.36	$214.35	$214.40
Purchase #3	$85.59	7.126%	$91.6891	$91.69	$91.70	$91.70
Purchase #4	$175.85	5.732%	$185.9297	$185.93	$185.95	$185.90
Purchase #5	$98.61	6.634%	$105.1518	$105.15	$105.15	$105.20
Purchase #6	$149.73	6.579%	$159.5807	$159.58	$159.60	$159.60
Purchase #7	$122.26	7.757%	$131.7437	$131.74	$131.75	$131.70
7 purchase totals =	$1,042.51		$1,126.9106	$1,126.90	$1,126.95	$1,127.00