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	$92.54	4.434%	$96.6432	$96.64	$96.65	$96.60
Purchase #2	$175.50	3.455%	$181.5635	$181.56	$181.55	$181.60
Purchase #3	$54.59	5.222%	$57.4407	$57.44	$57.45	$57.40
Purchase #4	$25.78	5.191%	$27.1182	$27.12	$27.10	$27.10
Purchase #5	$196.93	10.344%	$217.3004	$217.30	$217.30	$217.30
Purchase #6	$114.38	11.158%	$127.1425	$127.14	$127.15	$127.10
Purchase #7	$169.69	5.616%	$179.2198	$179.22	$179.20	$179.20
7 purchase totals =	$829.41		$886.4283	$886.42	$886.40	$886.30