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	$141.51	8.864%	$154.0534	$154.05	$154.05	$154.10
Purchase #2	$229.87	6.820%	$245.5471	$245.55	$245.55	$245.50
Purchase #3	$113.87	8.390%	$123.4237	$123.42	$123.40	$123.40
Purchase #4	$112.62	9.667%	$123.507	$123.51	$123.50	$123.50
Purchase #5	$96.91	10.845%	$107.4199	$107.42	$107.40	$107.40
Purchase #6	$10.52	8.765%	$11.4421	$11.44	$11.45	$11.40
Purchase #7	$219.80	13.786%	$250.1016	$250.10	$250.10	$250.10
7 purchase totals =	$925.10		$1,015.4948	$1,015.49	$1,015.45	$1,015.40