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	$117.69	8.205%	$127.3465	$127.35	$127.35	$127.30
Purchase #2	$73.26	10.347%	$80.8402	$80.84	$80.85	$80.80
Purchase #3	$105.59	4.157%	$109.9794	$109.98	$110.00	$110.00
Purchase #4	$41.29	9.649%	$45.2741	$45.27	$45.25	$45.30
Purchase #5	$29.72	9.287%	$32.4801	$32.48	$32.50	$32.50
Purchase #6	$243.70	7.761%	$262.6136	$262.61	$262.60	$262.60
Purchase #7	$226.75	4.453%	$236.8472	$236.85	$236.85	$236.80
7 purchase totals =	$838.00		$895.3811	$895.38	$895.40	$895.30