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	$117.59	10.623%	$130.0816	$130.08	$130.10	$130.10
Purchase #2	$153.89	4.333%	$160.5581	$160.56	$160.55	$160.60
Purchase #3	$35.40	11.251%	$39.3829	$39.38	$39.40	$39.40
Purchase #4	$144.27	10.660%	$159.6492	$159.65	$159.65	$159.60
Purchase #5	$13.37	8.829%	$14.5504	$14.55	$14.55	$14.60
Purchase #6	$178.68	12.111%	$200.3199	$200.32	$200.30	$200.30
Purchase #7	$19.57	4.372%	$20.4256	$20.43	$20.45	$20.40
7 purchase totals =	$662.77		$724.9677	$724.97	$725.00	$725.00