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	$177.98	4.414%	$185.836	$185.84	$185.85	$185.80
Purchase #2	$96.90	9.200%	$105.8148	$105.81	$105.80	$105.80
Purchase #3	$205.91	8.268%	$222.9346	$222.93	$222.95	$222.90
Purchase #4	$10.27	3.174%	$10.596	$10.60	$10.60	$10.60
Purchase #5	$47.58	6.306%	$50.5804	$50.58	$50.60	$50.60
Purchase #6	$248.66	6.736%	$265.4097	$265.41	$265.40	$265.40
Purchase #7	$154.35	11.805%	$172.571	$172.57	$172.55	$172.60
7 purchase totals =	$941.65		$1,013.7425	$1,013.74	$1,013.75	$1,013.70