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	$175.50	10.845%	$194.533	$194.53	$194.55	$194.50
Purchase #2	$5.76	4.721%	$6.0319	$6.03	$6.05	$6.00
Purchase #3	$78.83	4.642%	$82.4893	$82.49	$82.50	$82.50
Purchase #4	$138.86	11.699%	$155.1052	$155.11	$155.10	$155.10
Purchase #5	$182.94	11.583%	$204.1299	$204.13	$204.15	$204.10
Purchase #6	$210.97	8.286%	$228.451	$228.45	$228.45	$228.50
Purchase #7	$99.87	3.675%	$103.5402	$103.54	$103.55	$103.50
7 purchase totals =	$892.73		$974.2805	$974.28	$974.35	$974.20