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	$87.79	8.231%	$95.016	$95.02	$95.00	$95.00
Purchase #2	$231.61	9.723%	$254.1294	$254.13	$254.15	$254.10
Purchase #3	$125.31	10.244%	$138.1468	$138.15	$138.15	$138.10
Purchase #4	$144.61	4.504%	$151.1232	$151.12	$151.10	$151.10
Purchase #5	$164.40	9.401%	$179.8552	$179.86	$179.85	$179.90
Purchase #6	$140.87	8.141%	$152.3382	$152.34	$152.35	$152.30
Purchase #7	$90.56	9.811%	$99.4448	$99.44	$99.45	$99.40
7 purchase totals =	$985.15		$1,070.0536	$1,070.06	$1,070.05	$1,069.90