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	$115.38	10.194%	$127.1418	$127.14	$127.15	$127.10
Purchase #2	$17.69	4.536%	$18.4924	$18.49	$18.50	$18.50
Purchase #3	$133.35	11.671%	$148.9133	$148.91	$148.90	$148.90
Purchase #4	$222.73	13.753%	$253.3621	$253.36	$253.35	$253.40
Purchase #5	$101.38	13.414%	$114.9791	$114.98	$115.00	$115.00
Purchase #6	$149.37	8.109%	$161.4824	$161.48	$161.50	$161.50
Purchase #7	$189.46	5.436%	$199.759	$199.76	$199.75	$199.80
7 purchase totals =	$929.36		$1,024.1301	$1,024.12	$1,024.15	$1,024.20