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	$106.59	4.689%	$111.588	$111.59	$111.60	$111.60
Purchase #2	$36.56	8.228%	$39.5682	$39.57	$39.55	$39.60
Purchase #3	$242.29	6.775%	$258.7051	$258.71	$258.70	$258.70
Purchase #4	$217.65	5.701%	$230.0582	$230.06	$230.05	$230.10
Purchase #5	$249.97	4.672%	$261.6486	$261.65	$261.65	$261.60
Purchase #6	$31.43	8.628%	$34.1418	$34.14	$34.15	$34.10
Purchase #7	$64.32	13.228%	$72.8282	$72.83	$72.85	$72.80
7 purchase totals =	$948.81		$1,008.5381	$1,008.55	$1,008.55	$1,008.50