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	$64.90	7.463%	$69.7435	$69.74	$69.75	$69.70
Purchase #2	$216.79	13.482%	$246.0176	$246.02	$246.00	$246.00
Purchase #3	$34.62	8.363%	$37.5153	$37.52	$37.50	$37.50
Purchase #4	$181.79	13.163%	$205.719	$205.72	$205.70	$205.70
Purchase #5	$126.85	12.298%	$142.45	$142.45	$142.45	$142.50
Purchase #6	$149.25	10.751%	$165.2959	$165.30	$165.30	$165.30
Purchase #7	$142.80	11.109%	$158.6637	$158.66	$158.65	$158.70
7 purchase totals =	$917.00		$1,025.4050	$1,025.41	$1,025.35	$1,025.40