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	$168.86	4.514%	$176.4823	$176.48	$176.50	$176.50
Purchase #2	$22.49	11.543%	$25.086	$25.09	$25.10	$25.10
Purchase #3	$30.93	7.850%	$33.358	$33.36	$33.35	$33.40
Purchase #4	$50.87	7.221%	$54.5433	$54.54	$54.55	$54.50
Purchase #5	$57.97	6.594%	$61.7925	$61.79	$61.80	$61.80
Purchase #6	$233.70	13.182%	$264.5063	$264.51	$264.50	$264.50
Purchase #7	$59.32	3.617%	$61.4656	$61.47	$61.45	$61.50
7 purchase totals =	$624.14		$677.2340	$677.24	$677.25	$677.30