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	$234.64	7.223%	$251.588	$251.59	$251.60	$251.60
Purchase #2	$41.43	10.713%	$45.8684	$45.87	$45.85	$45.90
Purchase #3	$78.28	5.329%	$82.4515	$82.45	$82.45	$82.50
Purchase #4	$238.34	5.526%	$251.5107	$251.51	$251.50	$251.50
Purchase #5	$105.36	3.843%	$109.409	$109.41	$109.40	$109.40
Purchase #6	$212.65	11.431%	$236.958	$236.96	$236.95	$237.00
Purchase #7	$178.28	6.729%	$190.2765	$190.28	$190.30	$190.30
7 purchase totals =	$1,088.98		$1,168.0621	$1,168.07	$1,168.05	$1,168.20