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	$214.38	7.134%	$229.6739	$229.67	$229.65	$229.70
Purchase #2	$160.50	7.450%	$172.4573	$172.46	$172.45	$172.50
Purchase #3	$109.54	12.764%	$123.5217	$123.52	$123.50	$123.50
Purchase #4	$190.39	9.443%	$208.3685	$208.37	$208.35	$208.40
Purchase #5	$102.50	7.463%	$110.1496	$110.15	$110.15	$110.10
Purchase #6	$219.99	3.333%	$227.3223	$227.32	$227.30	$227.30
Purchase #7	$145.46	5.143%	$152.941	$152.94	$152.95	$152.90
7 purchase totals =	$1,142.76		$1,224.4343	$1,224.43	$1,224.35	$1,224.40