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	$100.94	10.812%	$111.8536	$111.85	$111.85	$111.90
Purchase #2	$20.39	4.388%	$21.2847	$21.28	$21.30	$21.30
Purchase #3	$72.55	5.624%	$76.6302	$76.63	$76.65	$76.60
Purchase #4	$211.33	3.533%	$218.7963	$218.80	$218.80	$218.80
Purchase #5	$165.95	11.723%	$185.4043	$185.40	$185.40	$185.40
Purchase #6	$127.91	4.748%	$133.9832	$133.98	$134.00	$134.00
Purchase #7	$157.82	12.369%	$177.3408	$177.34	$177.35	$177.30
7 purchase totals =	$856.89		$925.2931	$925.28	$925.35	$925.30