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	$209.88	3.461%	$217.1439	$217.14	$217.15	$217.10
Purchase #2	$20.53	4.839%	$21.5234	$21.52	$21.50	$21.50
Purchase #3	$56.82	8.341%	$61.5594	$61.56	$61.55	$61.60
Purchase #4	$147.86	5.572%	$156.0988	$156.10	$156.10	$156.10
Purchase #5	$45.98	12.540%	$51.7459	$51.75	$51.75	$51.70
Purchase #6	$32.94	13.663%	$37.4406	$37.44	$37.45	$37.40
Purchase #7	$181.95	8.721%	$197.8179	$197.82	$197.80	$197.80
7 purchase totals =	$695.96		$743.3299	$743.33	$743.30	$743.20