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	$214.25	4.672%	$224.2598	$224.26	$224.25	$224.30
Purchase #2	$235.28	12.445%	$264.5606	$264.56	$264.55	$264.60
Purchase #3	$75.68	8.666%	$82.2384	$82.24	$82.25	$82.20
Purchase #4	$40.41	12.317%	$45.3873	$45.39	$45.40	$45.40
Purchase #5	$87.50	5.323%	$92.1576	$92.16	$92.15	$92.20
Purchase #6	$176.25	7.614%	$189.6697	$189.67	$189.65	$189.70
Purchase #7	$112.64	10.162%	$124.0865	$124.09	$124.10	$124.10
7 purchase totals =	$942.01		$1,022.3599	$1,022.37	$1,022.35	$1,022.50