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	$197.27	13.217%	$223.3432	$223.34	$223.35	$223.30
Purchase #2	$148.54	13.861%	$169.1291	$169.13	$169.15	$169.10
Purchase #3	$186.59	4.236%	$194.494	$194.49	$194.50	$194.50
Purchase #4	$52.87	12.145%	$59.2911	$59.29	$59.30	$59.30
Purchase #5	$129.58	10.801%	$143.5759	$143.58	$143.60	$143.60
Purchase #6	$159.76	5.201%	$168.0691	$168.07	$168.05	$168.10
Purchase #7	$103.68	5.864%	$109.7598	$109.76	$109.75	$109.80
7 purchase totals =	$978.29		$1,067.6622	$1,067.66	$1,067.70	$1,067.70