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	$90.43	4.663%	$94.6468	$94.65	$94.65	$94.60
Purchase #2	$142.29	11.145%	$158.1482	$158.15	$158.15	$158.10
Purchase #3	$160.79	4.816%	$168.5336	$168.53	$168.55	$168.50
Purchase #4	$47.79	11.838%	$53.4474	$53.45	$53.45	$53.40
Purchase #5	$242.91	6.173%	$257.9048	$257.90	$257.90	$257.90
Purchase #6	$20.33	10.491%	$22.4628	$22.46	$22.45	$22.50
Purchase #7	$243.78	13.821%	$277.4728	$277.47	$277.45	$277.50
7 purchase totals =	$948.32		$1,032.6164	$1,032.61	$1,032.60	$1,032.50