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	$194.54	12.575%	$219.0034	$219.00	$219.00	$219.00
Purchase #2	$155.55	3.745%	$161.3753	$161.38	$161.40	$161.40
Purchase #3	$93.92	4.488%	$98.1351	$98.14	$98.15	$98.10
Purchase #4	$65.47	12.436%	$73.6118	$73.61	$73.60	$73.60
Purchase #5	$167.91	12.383%	$188.7023	$188.70	$188.70	$188.70
Purchase #6	$173.89	6.667%	$185.4832	$185.48	$185.50	$185.50
Purchase #7	$205.94	6.789%	$219.9213	$219.92	$219.90	$219.90
7 purchase totals =	$1,057.22		$1,146.2324	$1,146.23	$1,146.25	$1,146.20