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	$211.72	11.405%	$235.8667	$235.87	$235.85	$235.90
Purchase #2	$209.75	13.510%	$238.0872	$238.09	$238.10	$238.10
Purchase #3	$68.29	3.187%	$70.4664	$70.47	$70.45	$70.50
Purchase #4	$102.66	10.224%	$113.156	$113.16	$113.15	$113.20
Purchase #5	$70.89	13.716%	$80.6133	$80.61	$80.60	$80.60
Purchase #6	$86.49	10.460%	$95.5369	$95.54	$95.55	$95.50
Purchase #7	$160.50	6.747%	$171.3289	$171.33	$171.35	$171.30
7 purchase totals =	$910.30		$1,005.0554	$1,005.07	$1,005.05	$1,005.10