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	$104.93	4.734%	$109.8974	$109.90	$109.90	$109.90
Purchase #2	$10.44	11.638%	$11.655	$11.66	$11.65	$11.70
Purchase #3	$126.36	4.797%	$132.4215	$132.42	$132.40	$132.40
Purchase #4	$169.95	12.739%	$191.5999	$191.60	$191.60	$191.60
Purchase #5	$112.56	13.168%	$127.3819	$127.38	$127.40	$127.40
Purchase #6	$136.78	12.801%	$154.2892	$154.29	$154.30	$154.30
Purchase #7	$129.96	13.410%	$147.3876	$147.39	$147.40	$147.40
7 purchase totals =	$790.98		$874.6325	$874.64	$874.65	$874.70