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	$188.39	4.331%	$196.5492	$196.55	$196.55	$196.50
Purchase #2	$137.55	5.681%	$145.3642	$145.36	$145.35	$145.40
Purchase #3	$95.33	5.759%	$100.8201	$100.82	$100.80	$100.80
Purchase #4	$67.30	5.456%	$70.9719	$70.97	$70.95	$71.00
Purchase #5	$127.77	10.463%	$141.1386	$141.14	$141.15	$141.10
Purchase #6	$16.37	11.155%	$18.1961	$18.20	$18.20	$18.20
Purchase #7	$42.53	9.104%	$46.4019	$46.40	$46.40	$46.40
7 purchase totals =	$675.24		$719.4420	$719.44	$719.40	$719.40