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	$212.54	10.508%	$234.8737	$234.87	$234.85	$234.90
Purchase #2	$43.66	4.744%	$45.7312	$45.73	$45.75	$45.70
Purchase #3	$197.57	12.436%	$222.1398	$222.14	$222.15	$222.10
Purchase #4	$124.29	10.699%	$137.5878	$137.59	$137.60	$137.60
Purchase #5	$176.38	13.489%	$200.1719	$200.17	$200.15	$200.20
Purchase #6	$188.70	6.422%	$200.8183	$200.82	$200.80	$200.80
Purchase #7	$62.40	5.541%	$65.8576	$65.86	$65.85	$65.90
7 purchase totals =	$1,005.54		$1,107.1803	$1,107.18	$1,107.15	$1,107.20