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	$71.28	10.341%	$78.6511	$78.65	$78.65	$78.70
Purchase #2	$11.28	12.511%	$12.6912	$12.69	$12.70	$12.70
Purchase #3	$38.29	7.704%	$41.2399	$41.24	$41.25	$41.20
Purchase #4	$223.51	5.205%	$235.1437	$235.14	$235.15	$235.10
Purchase #5	$142.72	6.556%	$152.0767	$152.08	$152.10	$152.10
Purchase #6	$72.61	6.700%	$77.4749	$77.47	$77.45	$77.50
Purchase #7	$191.45	10.247%	$211.0679	$211.07	$211.05	$211.10
7 purchase totals =	$751.14		$808.3454	$808.34	$808.35	$808.40