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	$181.52	11.255%	$201.9501	$201.95	$201.95	$202.00
Purchase #2	$214.72	4.108%	$223.5407	$223.54	$223.55	$223.50
Purchase #3	$101.78	7.800%	$109.7188	$109.72	$109.70	$109.70
Purchase #4	$148.78	6.840%	$158.9566	$158.96	$158.95	$159.00
Purchase #5	$113.86	6.373%	$121.1163	$121.12	$121.10	$121.10
Purchase #6	$203.39	5.338%	$214.247	$214.25	$214.25	$214.20
Purchase #7	$172.75	13.622%	$196.282	$196.28	$196.30	$196.30
7 purchase totals =	$1,136.80		$1,225.8115	$1,225.82	$1,225.80	$1,225.80