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	$214.70	12.483%	$241.501	$241.50	$241.50	$241.50
Purchase #2	$203.51	3.361%	$210.35	$210.35	$210.35	$210.40
Purchase #3	$234.83	12.552%	$264.3059	$264.31	$264.30	$264.30
Purchase #4	$50.92	9.125%	$55.5665	$55.57	$55.55	$55.60
Purchase #5	$91.34	5.849%	$96.6825	$96.68	$96.70	$96.70
Purchase #6	$66.88	7.455%	$71.8659	$71.87	$71.85	$71.90
Purchase #7	$13.59	3.753%	$14.1	$14.10	$14.10	$14.10
7 purchase totals =	$875.77		$954.3718	$954.38	$954.35	$954.50