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	$115.92	8.339%	$125.5866	$125.59	$125.60	$125.60
Purchase #2	$123.97	8.291%	$134.2484	$134.25	$134.25	$134.20
Purchase #3	$85.72	5.130%	$90.1174	$90.12	$90.10	$90.10
Purchase #4	$81.61	11.251%	$90.7919	$90.79	$90.80	$90.80
Purchase #5	$136.70	3.361%	$141.2945	$141.29	$141.30	$141.30
Purchase #6	$212.52	13.836%	$241.9243	$241.92	$241.90	$241.90
Purchase #7	$212.89	7.809%	$229.5146	$229.51	$229.50	$229.50
7 purchase totals =	$969.33		$1,053.4777	$1,053.47	$1,053.45	$1,053.40