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	$197.92	9.431%	$216.5858	$216.59	$216.60	$216.60
Purchase #2	$134.42	9.738%	$147.5098	$147.51	$147.50	$147.50
Purchase #3	$86.50	13.607%	$98.2701	$98.27	$98.25	$98.30
Purchase #4	$43.66	4.730%	$45.7251	$45.73	$45.75	$45.70
Purchase #5	$165.92	10.193%	$182.8322	$182.83	$182.85	$182.80
Purchase #6	$162.27	10.472%	$179.2629	$179.26	$179.25	$179.30
Purchase #7	$244.92	3.452%	$253.3746	$253.37	$253.35	$253.40
7 purchase totals =	$1,035.61		$1,123.5605	$1,123.56	$1,123.55	$1,123.60