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	$162.68	11.796%	$181.8697	$181.87	$181.85	$181.90
Purchase #2	$201.41	9.125%	$219.7887	$219.79	$219.80	$219.80
Purchase #3	$78.46	6.820%	$83.811	$83.81	$83.80	$83.80
Purchase #4	$82.64	9.366%	$90.3801	$90.38	$90.40	$90.40
Purchase #5	$175.38	13.869%	$199.7035	$199.70	$199.70	$199.70
Purchase #6	$111.77	10.251%	$123.2275	$123.23	$123.25	$123.20
Purchase #7	$146.52	10.286%	$161.591	$161.59	$161.60	$161.60
7 purchase totals =	$958.86		$1,060.3715	$1,060.37	$1,060.40	$1,060.40