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	$219.50	7.482%	$235.923	$235.92	$235.90	$235.90
Purchase #2	$51.73	4.113%	$53.8577	$53.86	$53.85	$53.90
Purchase #3	$40.68	5.226%	$42.8059	$42.81	$42.80	$42.80
Purchase #4	$32.84	13.824%	$37.3798	$37.38	$37.40	$37.40
Purchase #5	$171.62	4.649%	$179.5986	$179.60	$179.60	$179.60
Purchase #6	$145.98	11.245%	$162.3955	$162.40	$162.40	$162.40
Purchase #7	$208.76	3.852%	$216.8014	$216.80	$216.80	$216.80
7 purchase totals =	$871.11		$928.7619	$928.77	$928.75	$928.80