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	$144.27	7.671%	$155.337	$155.34	$155.35	$155.30
Purchase #2	$100.77	10.607%	$111.4587	$111.46	$111.45	$111.50
Purchase #3	$64.82	7.851%	$69.909	$69.91	$69.90	$69.90
Purchase #4	$227.53	6.298%	$241.8598	$241.86	$241.85	$241.90
Purchase #5	$58.52	11.547%	$65.2773	$65.28	$65.30	$65.30
Purchase #6	$222.80	12.324%	$250.2579	$250.26	$250.25	$250.30
Purchase #7	$213.90	5.721%	$226.1372	$226.14	$226.15	$226.10
7 purchase totals =	$1,032.61		$1,120.2369	$1,120.25	$1,120.25	$1,120.30