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	$178.60	9.858%	$196.2064	$196.21	$196.20	$196.20
Purchase #2	$17.54	12.672%	$19.7627	$19.76	$19.75	$19.80
Purchase #3	$142.40	9.630%	$156.1131	$156.11	$156.10	$156.10
Purchase #4	$65.86	10.609%	$72.8471	$72.85	$72.85	$72.80
Purchase #5	$203.41	13.364%	$230.5937	$230.59	$230.60	$230.60
Purchase #6	$242.83	4.540%	$253.8545	$253.85	$253.85	$253.90
Purchase #7	$117.51	12.560%	$132.2693	$132.27	$132.25	$132.30
7 purchase totals =	$968.15		$1,061.6468	$1,061.64	$1,061.60	$1,061.70