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	$86.34	11.135%	$95.954	$95.95	$95.95	$96.00
Purchase #2	$98.31	11.657%	$109.77	$109.77	$109.75	$109.80
Purchase #3	$141.41	11.317%	$157.4134	$157.41	$157.40	$157.40
Purchase #4	$58.77	12.746%	$66.2608	$66.26	$66.25	$66.30
Purchase #5	$246.98	11.114%	$274.4294	$274.43	$274.45	$274.40
Purchase #6	$101.67	9.323%	$111.1487	$111.15	$111.15	$111.10
Purchase #7	$242.55	9.296%	$265.0974	$265.10	$265.10	$265.10
7 purchase totals =	$976.03		$1,080.0737	$1,080.07	$1,080.05	$1,080.10