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	$146.39	4.213%	$152.5574	$152.56	$152.55	$152.60
Purchase #2	$200.96	13.536%	$228.1619	$228.16	$228.15	$228.20
Purchase #3	$178.48	7.713%	$192.2462	$192.25	$192.25	$192.20
Purchase #4	$13.26	4.847%	$13.9027	$13.90	$13.90	$13.90
Purchase #5	$183.67	9.191%	$200.5511	$200.55	$200.55	$200.60
Purchase #6	$195.63	5.111%	$205.6286	$205.63	$205.65	$205.60
Purchase #7	$118.53	4.321%	$123.6517	$123.65	$123.65	$123.70
7 purchase totals =	$1,036.92		$1,116.6996	$1,116.70	$1,116.70	$1,116.80