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	$78.70	10.562%	$87.0123	$87.01	$87.00	$87.00
Purchase #2	$194.39	11.773%	$217.2755	$217.28	$217.30	$217.30
Purchase #3	$82.34	9.605%	$90.2488	$90.25	$90.25	$90.20
Purchase #4	$117.29	11.352%	$130.6048	$130.60	$130.60	$130.60
Purchase #5	$235.85	13.853%	$268.5223	$268.52	$268.50	$268.50
Purchase #6	$166.91	11.257%	$185.6991	$185.70	$185.70	$185.70
Purchase #7	$160.27	7.812%	$172.7903	$172.79	$172.80	$172.80
7 purchase totals =	$1,035.75		$1,152.1531	$1,152.15	$1,152.15	$1,152.10