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	$191.56	4.858%	$200.866	$200.87	$200.85	$200.90
Purchase #2	$34.61	9.285%	$37.8235	$37.82	$37.80	$37.80
Purchase #3	$71.81	5.248%	$75.5786	$75.58	$75.60	$75.60
Purchase #4	$28.56	4.521%	$29.8512	$29.85	$29.85	$29.90
Purchase #5	$190.52	12.459%	$214.2569	$214.26	$214.25	$214.30
Purchase #6	$234.78	8.754%	$255.3326	$255.33	$255.35	$255.30
Purchase #7	$242.40	9.381%	$265.1395	$265.14	$265.15	$265.10
7 purchase totals =	$994.24		$1,078.8483	$1,078.85	$1,078.85	$1,078.90