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	$211.56	10.280%	$233.3084	$233.31	$233.30	$233.30
Purchase #2	$223.92	13.252%	$253.5939	$253.59	$253.60	$253.60
Purchase #3	$240.26	9.464%	$262.9982	$263.00	$263.00	$263.00
Purchase #4	$71.45	13.603%	$81.1693	$81.17	$81.15	$81.20
Purchase #5	$82.37	12.129%	$92.3607	$92.36	$92.35	$92.40
Purchase #6	$183.35	3.823%	$190.3595	$190.36	$190.35	$190.40
Purchase #7	$58.32	6.780%	$62.2741	$62.27	$62.25	$62.30
7 purchase totals =	$1,071.23		$1,176.0641	$1,176.06	$1,176.00	$1,176.20