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	$223.92	4.474%	$233.9382	$233.94	$233.95	$233.90
Purchase #2	$21.39	5.478%	$22.5617	$22.56	$22.55	$22.60
Purchase #3	$86.82	12.291%	$97.491	$97.49	$97.50	$97.50
Purchase #4	$148.87	11.134%	$165.4452	$165.45	$165.45	$165.40
Purchase #5	$171.76	11.526%	$191.5571	$191.56	$191.55	$191.60
Purchase #6	$220.37	9.581%	$241.4836	$241.48	$241.50	$241.50
Purchase #7	$224.37	7.819%	$241.9135	$241.91	$241.90	$241.90
7 purchase totals =	$1,097.50		$1,194.3903	$1,194.39	$1,194.40	$1,194.40