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	$200.59	4.662%	$209.9415	$209.94	$209.95	$209.90
Purchase #2	$212.38	11.671%	$237.1669	$237.17	$237.15	$237.20
Purchase #3	$117.90	7.586%	$126.8439	$126.84	$126.85	$126.80
Purchase #4	$19.33	4.194%	$20.1407	$20.14	$20.15	$20.10
Purchase #5	$36.44	10.396%	$40.2283	$40.23	$40.25	$40.20
Purchase #6	$145.72	11.794%	$162.9062	$162.91	$162.90	$162.90
Purchase #7	$238.87	8.550%	$259.2934	$259.29	$259.30	$259.30
7 purchase totals =	$971.23		$1,056.5209	$1,056.52	$1,056.55	$1,056.40