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	$173.31	10.850%	$192.1141	$192.11	$192.10	$192.10
Purchase #2	$46.54	4.248%	$48.517	$48.52	$48.50	$48.50
Purchase #3	$160.30	8.797%	$174.4016	$174.40	$174.40	$174.40
Purchase #4	$115.71	10.308%	$127.6374	$127.64	$127.65	$127.60
Purchase #5	$59.51	8.437%	$64.5309	$64.53	$64.55	$64.50
Purchase #6	$122.27	3.481%	$126.5262	$126.53	$126.55	$126.50
Purchase #7	$147.98	9.556%	$162.121	$162.12	$162.10	$162.10
7 purchase totals =	$825.62		$895.8482	$895.85	$895.85	$895.70