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	$241.49	8.727%	$262.5648	$262.56	$262.55	$262.60
Purchase #2	$244.94	8.242%	$265.128	$265.13	$265.15	$265.10
Purchase #3	$170.77	10.366%	$188.472	$188.47	$188.45	$188.50
Purchase #4	$42.93	12.441%	$48.2709	$48.27	$48.25	$48.30
Purchase #5	$167.76	3.377%	$173.4253	$173.43	$173.45	$173.40
Purchase #6	$83.76	9.810%	$91.9769	$91.98	$92.00	$92.00
Purchase #7	$139.86	10.388%	$154.3887	$154.39	$154.40	$154.40
7 purchase totals =	$1,091.51		$1,184.2266	$1,184.23	$1,184.25	$1,184.30