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	$224.67	10.643%	$248.5816	$248.58	$248.60	$248.60
Purchase #2	$234.39	3.820%	$243.3437	$243.34	$243.35	$243.30
Purchase #3	$183.30	7.106%	$196.3253	$196.33	$196.35	$196.30
Purchase #4	$59.52	11.307%	$66.2499	$66.25	$66.25	$66.20
Purchase #5	$125.33	3.837%	$130.1389	$130.14	$130.15	$130.10
Purchase #6	$218.89	4.346%	$228.403	$228.40	$228.40	$228.40
Purchase #7	$57.67	6.586%	$61.4681	$61.47	$61.45	$61.50
7 purchase totals =	$1,103.77		$1,174.5105	$1,174.51	$1,174.55	$1,174.40