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	$127.82	10.532%	$141.282	$141.28	$141.30	$141.30
Purchase #2	$233.33	9.537%	$255.5827	$255.58	$255.60	$255.60
Purchase #3	$238.25	12.521%	$268.0813	$268.08	$268.10	$268.10
Purchase #4	$17.88	8.715%	$19.4382	$19.44	$19.45	$19.40
Purchase #5	$228.45	3.467%	$236.3704	$236.37	$236.35	$236.40
Purchase #6	$78.32	5.375%	$82.5297	$82.53	$82.55	$82.50
Purchase #7	$18.49	4.153%	$19.2579	$19.26	$19.25	$19.30
7 purchase totals =	$942.54		$1,022.5422	$1,022.54	$1,022.60	$1,022.60