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	$54.92	13.283%	$62.215	$62.22	$62.20	$62.20
Purchase #2	$35.63	6.139%	$37.8173	$37.82	$37.80	$37.80
Purchase #3	$144.37	12.401%	$162.2733	$162.27	$162.25	$162.30
Purchase #4	$207.61	12.550%	$233.6651	$233.67	$233.65	$233.70
Purchase #5	$195.41	9.813%	$214.5856	$214.59	$214.60	$214.60
Purchase #6	$132.84	9.451%	$145.3947	$145.39	$145.40	$145.40
Purchase #7	$68.49	12.400%	$76.9828	$76.98	$77.00	$77.00
7 purchase totals =	$839.27		$932.9338	$932.94	$932.90	$933.00