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	$114.76	9.289%	$125.4201	$125.42	$125.40	$125.40
Purchase #2	$16.37	9.405%	$17.9096	$17.91	$17.90	$17.90
Purchase #3	$43.68	3.829%	$45.3525	$45.35	$45.35	$45.40
Purchase #4	$95.60	5.140%	$100.5138	$100.51	$100.50	$100.50
Purchase #5	$6.29	12.603%	$7.0827	$7.08	$7.10	$7.10
Purchase #6	$124.70	12.470%	$140.2501	$140.25	$140.25	$140.30
Purchase #7	$38.46	4.774%	$40.2961	$40.30	$40.30	$40.30
7 purchase totals =	$439.86		$476.8249	$476.82	$476.80	$476.90