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	$184.67	4.351%	$192.705	$192.71	$192.70	$192.70
Purchase #2	$213.49	6.451%	$227.2622	$227.26	$227.25	$227.30
Purchase #3	$82.29	9.742%	$90.3067	$90.31	$90.30	$90.30
Purchase #4	$99.97	5.168%	$105.1364	$105.14	$105.15	$105.10
Purchase #5	$248.32	11.577%	$277.068	$277.07	$277.05	$277.10
Purchase #6	$97.82	13.188%	$110.7205	$110.72	$110.70	$110.70
Purchase #7	$88.70	4.566%	$92.75	$92.75	$92.75	$92.80
7 purchase totals =	$1,015.26		$1,095.9488	$1,095.96	$1,095.90	$1,096.00