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	$215.59	4.424%	$225.1277	$225.13	$225.15	$225.10
Purchase #2	$54.50	8.798%	$59.2949	$59.29	$59.30	$59.30
Purchase #3	$190.99	3.563%	$197.795	$197.80	$197.80	$197.80
Purchase #4	$93.53	6.842%	$99.9293	$99.93	$99.95	$99.90
Purchase #5	$146.85	4.647%	$153.6741	$153.67	$153.65	$153.70
Purchase #6	$34.95	7.789%	$37.6723	$37.67	$37.65	$37.70
Purchase #7	$225.28	10.731%	$249.4548	$249.45	$249.45	$249.50
7 purchase totals =	$961.69		$1,022.9481	$1,022.94	$1,022.95	$1,023.00