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	$191.31	10.765%	$211.9045	$211.90	$211.90	$211.90
Purchase #2	$75.78	10.319%	$83.5997	$83.60	$83.60	$83.60
Purchase #3	$220.88	4.424%	$230.6517	$230.65	$230.65	$230.70
Purchase #4	$149.52	7.598%	$160.8805	$160.88	$160.90	$160.90
Purchase #5	$139.40	5.647%	$147.2719	$147.27	$147.25	$147.30
Purchase #6	$37.94	13.183%	$42.9416	$42.94	$42.95	$42.90
Purchase #7	$141.75	13.314%	$160.6226	$160.62	$160.60	$160.60
7 purchase totals =	$956.58		$1,037.8725	$1,037.86	$1,037.85	$1,037.90