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	$141.32	10.258%	$155.8166	$155.82	$155.80	$155.80
Purchase #2	$129.73	3.806%	$134.6675	$134.67	$134.65	$134.70
Purchase #3	$85.79	5.583%	$90.5797	$90.58	$90.60	$90.60
Purchase #4	$173.40	10.479%	$191.5706	$191.57	$191.55	$191.60
Purchase #5	$212.98	6.834%	$227.5351	$227.54	$227.55	$227.50
Purchase #6	$102.57	6.670%	$109.4114	$109.41	$109.40	$109.40
Purchase #7	$145.50	5.518%	$153.5287	$153.53	$153.55	$153.50
7 purchase totals =	$991.29		$1,063.1096	$1,063.12	$1,063.10	$1,063.10