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	$71.95	4.122%	$74.9158	$74.92	$74.90	$74.90
Purchase #2	$79.43	3.366%	$82.1036	$82.10	$82.10	$82.10
Purchase #3	$247.64	5.809%	$262.0254	$262.03	$262.05	$262.00
Purchase #4	$106.53	7.277%	$114.2822	$114.28	$114.30	$114.30
Purchase #5	$218.71	3.151%	$225.6016	$225.60	$225.60	$225.60
Purchase #6	$154.41	4.196%	$160.889	$160.89	$160.90	$160.90
Purchase #7	$103.80	8.472%	$112.5939	$112.59	$112.60	$112.60
7 purchase totals =	$982.47		$1,032.4115	$1,032.41	$1,032.45	$1,032.40