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	$181.74	10.377%	$200.5992	$200.60	$200.60	$200.60
Purchase #2	$29.77	11.450%	$33.1787	$33.18	$33.20	$33.20
Purchase #3	$181.77	8.308%	$196.8715	$196.87	$196.85	$196.90
Purchase #4	$238.25	10.370%	$262.9565	$262.96	$262.95	$263.00
Purchase #5	$44.87	12.149%	$50.3213	$50.32	$50.30	$50.30
Purchase #6	$104.47	12.714%	$117.7523	$117.75	$117.75	$117.80
Purchase #7	$184.87	13.399%	$209.6407	$209.64	$209.65	$209.60
7 purchase totals =	$965.74		$1,071.3202	$1,071.32	$1,071.30	$1,071.40