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	$101.39	11.202%	$112.7477	$112.75	$112.75	$112.70
Purchase #2	$19.28	12.282%	$21.648	$21.65	$21.65	$21.60
Purchase #3	$43.34	3.492%	$44.8534	$44.85	$44.85	$44.90
Purchase #4	$80.98	3.358%	$83.6993	$83.70	$83.70	$83.70
Purchase #5	$59.52	8.521%	$64.5917	$64.59	$64.60	$64.60
Purchase #6	$20.28	4.655%	$21.224	$21.22	$21.20	$21.20
Purchase #7	$105.66	3.755%	$109.6275	$109.63	$109.65	$109.60
7 purchase totals =	$430.45		$458.3916	$458.39	$458.40	$458.30