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	$149.91	4.181%	$156.1777	$156.18	$156.20	$156.20
Purchase #2	$12.93	5.449%	$13.6346	$13.63	$13.65	$13.60
Purchase #3	$93.32	13.401%	$105.8258	$105.83	$105.85	$105.80
Purchase #4	$184.97	11.234%	$205.7495	$205.75	$205.75	$205.70
Purchase #5	$247.30	3.202%	$255.2185	$255.22	$255.20	$255.20
Purchase #6	$151.77	11.573%	$169.3343	$169.33	$169.35	$169.30
Purchase #7	$144.71	5.660%	$152.9006	$152.90	$152.90	$152.90
7 purchase totals =	$984.91		$1,058.8410	$1,058.84	$1,058.90	$1,058.70