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	$183.82	8.446%	$199.3454	$199.35	$199.35	$199.30
Purchase #2	$59.55	6.288%	$63.2945	$63.29	$63.30	$63.30
Purchase #3	$106.56	4.577%	$111.4373	$111.44	$111.45	$111.40
Purchase #4	$207.60	4.440%	$216.8174	$216.82	$216.80	$216.80
Purchase #5	$184.27	9.268%	$201.3481	$201.35	$201.35	$201.30
Purchase #6	$93.76	10.649%	$103.7445	$103.74	$103.75	$103.70
Purchase #7	$116.42	9.216%	$127.1493	$127.15	$127.15	$127.10
7 purchase totals =	$951.98		$1,023.1365	$1,023.14	$1,023.15	$1,022.90