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	$187.67	3.666%	$194.55	$194.55	$194.55	$194.60
Purchase #2	$42.60	7.273%	$45.6983	$45.70	$45.70	$45.70
Purchase #3	$243.65	9.599%	$267.038	$267.04	$267.05	$267.00
Purchase #4	$231.80	9.640%	$254.1455	$254.15	$254.15	$254.10
Purchase #5	$71.63	10.116%	$78.8761	$78.88	$78.90	$78.90
Purchase #6	$52.58	11.518%	$58.6362	$58.64	$58.65	$58.60
Purchase #7	$220.65	10.852%	$244.5949	$244.59	$244.60	$244.60
7 purchase totals =	$1,050.58		$1,143.5390	$1,143.55	$1,143.60	$1,143.50