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	$162.57	7.390%	$174.5839	$174.58	$174.60	$174.60
Purchase #2	$70.84	11.387%	$78.9066	$78.91	$78.90	$78.90
Purchase #3	$155.31	12.573%	$174.8371	$174.84	$174.85	$174.80
Purchase #4	$51.55	8.420%	$55.8905	$55.89	$55.90	$55.90
Purchase #5	$205.75	13.305%	$233.125	$233.13	$233.15	$233.10
Purchase #6	$168.51	8.435%	$182.7238	$182.72	$182.70	$182.70
Purchase #7	$44.48	11.111%	$49.4222	$49.42	$49.40	$49.40
7 purchase totals =	$859.01		$949.4891	$949.49	$949.50	$949.40