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	$85.86	11.165%	$95.4463	$95.45	$95.45	$95.40
Purchase #2	$155.56	9.631%	$170.542	$170.54	$170.55	$170.50
Purchase #3	$199.92	7.634%	$215.1819	$215.18	$215.20	$215.20
Purchase #4	$149.96	8.123%	$162.1413	$162.14	$162.15	$162.10
Purchase #5	$42.51	13.745%	$48.353	$48.35	$48.35	$48.40
Purchase #6	$155.45	7.264%	$166.7419	$166.74	$166.75	$166.70
Purchase #7	$234.92	5.149%	$247.016	$247.02	$247.00	$247.00
7 purchase totals =	$1,024.18		$1,105.4224	$1,105.42	$1,105.45	$1,105.30