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	$200.59	11.253%	$223.1624	$223.16	$223.15	$223.20
Purchase #2	$176.43	4.710%	$184.7399	$184.74	$184.75	$184.70
Purchase #3	$202.74	10.592%	$224.2142	$224.21	$224.20	$224.20
Purchase #4	$17.36	6.638%	$18.5124	$18.51	$18.50	$18.50
Purchase #5	$55.40	11.657%	$61.858	$61.86	$61.85	$61.90
Purchase #6	$77.43	11.623%	$86.4297	$86.43	$86.45	$86.40
Purchase #7	$236.44	7.866%	$255.0384	$255.04	$255.05	$255.00
7 purchase totals =	$966.39		$1,053.9550	$1,053.95	$1,053.95	$1,053.90