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	$158.90	9.793%	$174.4611	$174.46	$174.45	$174.50
Purchase #2	$70.65	10.328%	$77.9467	$77.95	$77.95	$77.90
Purchase #3	$32.92	11.186%	$36.6024	$36.60	$36.60	$36.60
Purchase #4	$131.39	9.160%	$143.4253	$143.43	$143.45	$143.40
Purchase #5	$219.60	6.837%	$234.6141	$234.61	$234.60	$234.60
Purchase #6	$169.27	10.636%	$187.2736	$187.27	$187.25	$187.30
Purchase #7	$193.39	13.314%	$219.1379	$219.14	$219.15	$219.10
7 purchase totals =	$976.12		$1,073.4611	$1,073.46	$1,073.45	$1,073.40