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	$83.32	3.106%	$85.9079	$85.91	$85.90	$85.90
Purchase #2	$145.31	3.651%	$150.6153	$150.62	$150.60	$150.60
Purchase #3	$196.77	11.371%	$219.1447	$219.14	$219.15	$219.10
Purchase #4	$193.39	10.805%	$214.2858	$214.29	$214.30	$214.30
Purchase #5	$223.72	9.450%	$244.8615	$244.86	$244.85	$244.90
Purchase #6	$22.45	5.299%	$23.6396	$23.64	$23.65	$23.60
Purchase #7	$99.93	9.868%	$109.7911	$109.79	$109.80	$109.80
7 purchase totals =	$964.89		$1,048.2459	$1,048.25	$1,048.25	$1,048.20