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	$88.90	7.623%	$95.6768	$95.68	$95.70	$95.70
Purchase #2	$205.65	12.615%	$231.5927	$231.59	$231.60	$231.60
Purchase #3	$91.47	4.784%	$95.8459	$95.85	$95.85	$95.80
Purchase #4	$83.90	6.797%	$89.6027	$89.60	$89.60	$89.60
Purchase #5	$173.96	13.255%	$197.0184	$197.02	$197.00	$197.00
Purchase #6	$48.68	9.810%	$53.4555	$53.46	$53.45	$53.50
Purchase #7	$162.82	9.668%	$178.5614	$178.56	$178.55	$178.60
7 purchase totals =	$855.38		$941.7534	$941.76	$941.75	$941.80