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	$174.52	11.669%	$194.8847	$194.88	$194.90	$194.90
Purchase #2	$153.42	12.596%	$172.7448	$172.74	$172.75	$172.70
Purchase #3	$53.78	3.849%	$55.85	$55.85	$55.85	$55.90
Purchase #4	$152.31	10.679%	$168.5752	$168.58	$168.60	$168.60
Purchase #5	$80.98	5.306%	$85.2768	$85.28	$85.30	$85.30
Purchase #6	$228.55	7.807%	$246.3929	$246.39	$246.40	$246.40
Purchase #7	$174.39	3.409%	$180.335	$180.34	$180.35	$180.30
7 purchase totals =	$1,017.95		$1,104.0594	$1,104.06	$1,104.15	$1,104.10