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	$189.44	7.351%	$203.3657	$203.37	$203.35	$203.40
Purchase #2	$10.39	4.546%	$10.8623	$10.86	$10.85	$10.90
Purchase #3	$95.50	4.114%	$99.4289	$99.43	$99.45	$99.40
Purchase #4	$189.60	4.226%	$197.6125	$197.61	$197.60	$197.60
Purchase #5	$172.50	7.445%	$185.3426	$185.34	$185.35	$185.30
Purchase #6	$59.38	4.326%	$61.9488	$61.95	$61.95	$61.90
Purchase #7	$124.91	9.856%	$137.2211	$137.22	$137.20	$137.20
7 purchase totals =	$841.72		$895.7819	$895.78	$895.75	$895.70