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	$154.34	4.143%	$160.7343	$160.73	$160.75	$160.70
Purchase #2	$9.64	9.865%	$10.591	$10.59	$10.60	$10.60
Purchase #3	$52.58	3.400%	$54.3677	$54.37	$54.35	$54.40
Purchase #4	$174.34	12.498%	$196.129	$196.13	$196.15	$196.10
Purchase #5	$100.32	13.336%	$113.6987	$113.70	$113.70	$113.70
Purchase #6	$137.78	4.228%	$143.6053	$143.61	$143.60	$143.60
Purchase #7	$124.68	4.652%	$130.4801	$130.48	$130.50	$130.50
7 purchase totals =	$753.68		$809.6061	$809.61	$809.65	$809.60