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	$193.88	5.404%	$204.3573	$204.36	$204.35	$204.40
Purchase #2	$10.85	4.550%	$11.3437	$11.34	$11.35	$11.30
Purchase #3	$88.54	4.218%	$92.2746	$92.27	$92.25	$92.30
Purchase #4	$104.34	13.545%	$118.4729	$118.47	$118.45	$118.50
Purchase #5	$43.40	5.136%	$45.629	$45.63	$45.65	$45.60
Purchase #6	$64.88	12.261%	$72.8349	$72.83	$72.85	$72.80
Purchase #7	$227.31	3.847%	$236.0546	$236.05	$236.05	$236.10
7 purchase totals =	$733.20		$780.9670	$780.95	$780.95	$781.00