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	$173.69	4.593%	$181.6676	$181.67	$181.65	$181.70
Purchase #2	$161.97	3.388%	$167.4575	$167.46	$167.45	$167.50
Purchase #3	$13.55	7.118%	$14.5145	$14.51	$14.50	$14.50
Purchase #4	$77.62	5.183%	$81.643	$81.64	$81.65	$81.60
Purchase #5	$79.77	11.429%	$88.8869	$88.89	$88.90	$88.90
Purchase #6	$103.51	4.797%	$108.4754	$108.48	$108.50	$108.50
Purchase #7	$148.85	10.357%	$164.2664	$164.27	$164.25	$164.30
7 purchase totals =	$758.96		$806.9113	$806.92	$806.90	$807.00