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	$194.90	8.512%	$211.4899	$211.49	$211.50	$211.50
Purchase #2	$66.75	13.657%	$75.866	$75.87	$75.85	$75.90
Purchase #3	$205.45	10.381%	$226.7778	$226.78	$226.80	$226.80
Purchase #4	$185.52	13.822%	$211.1626	$211.16	$211.15	$211.20
Purchase #5	$109.72	13.822%	$124.8855	$124.89	$124.90	$124.90
Purchase #6	$158.56	13.247%	$179.5644	$179.56	$179.55	$179.60
Purchase #7	$28.90	11.138%	$32.1189	$32.12	$32.10	$32.10
7 purchase totals =	$949.80		$1,061.8651	$1,061.87	$1,061.85	$1,062.00