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	$168.95	7.531%	$181.6736	$181.67	$181.65	$181.70
Purchase #2	$161.62	6.434%	$172.0186	$172.02	$172.00	$172.00
Purchase #3	$53.54	9.281%	$58.509	$58.51	$58.50	$58.50
Purchase #4	$42.98	7.335%	$46.1326	$46.13	$46.15	$46.10
Purchase #5	$57.97	13.134%	$65.5838	$65.58	$65.60	$65.60
Purchase #6	$238.28	13.697%	$270.9172	$270.92	$270.90	$270.90
Purchase #7	$209.89	7.451%	$225.5289	$225.53	$225.55	$225.50
7 purchase totals =	$933.23		$1,020.3637	$1,020.36	$1,020.35	$1,020.30