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	$175.87	4.862%	$184.4208	$184.42	$184.40	$184.40
Purchase #2	$100.33	3.548%	$103.8897	$103.89	$103.90	$103.90
Purchase #3	$10.59	12.109%	$11.8723	$11.87	$11.85	$11.90
Purchase #4	$211.76	11.102%	$235.2696	$235.27	$235.25	$235.30
Purchase #5	$140.60	9.515%	$153.9781	$153.98	$154.00	$154.00
Purchase #6	$159.67	11.696%	$178.345	$178.35	$178.35	$178.30
Purchase #7	$174.30	3.567%	$180.5173	$180.52	$180.50	$180.50
7 purchase totals =	$973.12		$1,048.2928	$1,048.30	$1,048.25	$1,048.30