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	$188.59	13.714%	$214.4532	$214.45	$214.45	$214.50
Purchase #2	$165.85	5.188%	$174.4543	$174.45	$174.45	$174.50
Purchase #3	$227.32	7.398%	$244.1371	$244.14	$244.15	$244.10
Purchase #4	$81.95	4.218%	$85.4067	$85.41	$85.40	$85.40
Purchase #5	$179.79	10.613%	$198.8711	$198.87	$198.85	$198.90
Purchase #6	$97.37	12.111%	$109.1625	$109.16	$109.15	$109.20
Purchase #7	$229.51	6.762%	$245.0295	$245.03	$245.05	$245.00
7 purchase totals =	$1,170.38		$1,271.5144	$1,271.51	$1,271.50	$1,271.60