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	$175.75	10.769%	$194.6765	$194.68	$194.70	$194.70
Purchase #2	$75.34	13.677%	$85.6443	$85.64	$85.65	$85.60
Purchase #3	$137.71	10.488%	$152.153	$152.15	$152.15	$152.20
Purchase #4	$100.88	10.513%	$111.4855	$111.49	$111.50	$111.50
Purchase #5	$146.67	7.249%	$157.3021	$157.30	$157.30	$157.30
Purchase #6	$81.27	10.118%	$89.4929	$89.49	$89.50	$89.50
Purchase #7	$243.95	5.734%	$257.9381	$257.94	$257.95	$257.90
7 purchase totals =	$961.57		$1,048.6924	$1,048.69	$1,048.75	$1,048.70