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	$210.41	10.817%	$233.17	$233.17	$233.15	$233.20
Purchase #2	$99.61	7.193%	$106.7749	$106.77	$106.75	$106.80
Purchase #3	$153.77	13.514%	$174.5505	$174.55	$174.55	$174.60
Purchase #4	$160.94	13.191%	$182.1696	$182.17	$182.15	$182.20
Purchase #5	$157.61	5.848%	$166.827	$166.83	$166.85	$166.80
Purchase #6	$57.45	13.231%	$65.0512	$65.05	$65.05	$65.10
Purchase #7	$164.33	11.365%	$183.0061	$183.01	$183.00	$183.00
7 purchase totals =	$1,004.12		$1,111.5493	$1,111.55	$1,111.50	$1,111.70