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	$238.64	7.544%	$256.643	$256.64	$256.65	$256.60
Purchase #2	$100.34	11.171%	$111.549	$111.55	$111.55	$111.50
Purchase #3	$94.31	6.407%	$100.3524	$100.35	$100.35	$100.40
Purchase #4	$166.91	6.740%	$178.1597	$178.16	$178.15	$178.20
Purchase #5	$148.96	13.317%	$168.797	$168.80	$168.80	$168.80
Purchase #6	$39.41	3.656%	$40.8508	$40.85	$40.85	$40.90
Purchase #7	$239.41	13.651%	$272.0919	$272.09	$272.10	$272.10
7 purchase totals =	$1,027.98		$1,128.4438	$1,128.44	$1,128.45	$1,128.50