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	$96.30	9.481%	$105.4302	$105.43	$105.45	$105.40
Purchase #2	$21.73	4.322%	$22.6692	$22.67	$22.65	$22.70
Purchase #3	$232.39	10.390%	$256.5353	$256.54	$256.55	$256.50
Purchase #4	$15.78	8.367%	$17.1003	$17.10	$17.10	$17.10
Purchase #5	$172.50	10.810%	$191.1473	$191.15	$191.15	$191.10
Purchase #6	$167.45	6.602%	$178.505	$178.51	$178.50	$178.50
Purchase #7	$216.76	10.406%	$239.316	$239.32	$239.30	$239.30
7 purchase totals =	$922.91		$1,010.7033	$1,010.72	$1,010.70	$1,010.60