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	$43.35	3.410%	$44.8282	$44.83	$44.85	$44.80
Purchase #2	$135.29	13.774%	$153.9248	$153.92	$153.90	$153.90
Purchase #3	$188.36	6.265%	$200.1608	$200.16	$200.15	$200.20
Purchase #4	$93.65	6.369%	$99.6146	$99.61	$99.60	$99.60
Purchase #5	$61.64	8.627%	$66.9577	$66.96	$66.95	$67.00
Purchase #6	$47.55	6.423%	$50.6041	$50.60	$50.60	$50.60
Purchase #7	$89.45	12.637%	$100.7538	$100.75	$100.75	$100.80
7 purchase totals =	$659.29		$716.8440	$716.83	$716.80	$716.90