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	$207.63	8.603%	$225.4924	$225.49	$225.50	$225.50
Purchase #2	$184.56	6.482%	$196.5232	$196.52	$196.50	$196.50
Purchase #3	$212.91	9.606%	$233.3621	$233.36	$233.35	$233.40
Purchase #4	$27.64	8.339%	$29.9449	$29.94	$29.95	$29.90
Purchase #5	$208.75	12.235%	$234.2906	$234.29	$234.30	$234.30
Purchase #6	$166.83	3.283%	$172.307	$172.31	$172.30	$172.30
Purchase #7	$115.40	7.806%	$124.4081	$124.41	$124.40	$124.40
7 purchase totals =	$1,123.72		$1,216.3283	$1,216.32	$1,216.30	$1,216.30