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	$182.74	7.338%	$196.1495	$196.15	$196.15	$196.10
Purchase #2	$88.91	8.759%	$96.6976	$96.70	$96.70	$96.70
Purchase #3	$179.98	6.586%	$191.8335	$191.83	$191.85	$191.80
Purchase #4	$223.68	9.329%	$244.5471	$244.55	$244.55	$244.50
Purchase #5	$176.93	6.553%	$188.5242	$188.52	$188.50	$188.50
Purchase #6	$143.78	12.323%	$161.498	$161.50	$161.50	$161.50
Purchase #7	$74.91	11.649%	$83.6363	$83.64	$83.65	$83.60
7 purchase totals =	$1,070.93		$1,162.8862	$1,162.89	$1,162.90	$1,162.70