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	$236.54	10.794%	$262.0721	$262.07	$262.05	$262.10
Purchase #2	$188.81	12.650%	$212.6945	$212.69	$212.70	$212.70
Purchase #3	$225.94	6.269%	$240.1042	$240.10	$240.10	$240.10
Purchase #4	$189.90	8.128%	$205.3351	$205.34	$205.35	$205.30
Purchase #5	$51.69	3.470%	$53.4836	$53.48	$53.50	$53.50
Purchase #6	$37.96	4.476%	$39.6591	$39.66	$39.65	$39.70
Purchase #7	$83.54	6.618%	$89.0687	$89.07	$89.05	$89.10
7 purchase totals =	$1,014.38		$1,102.4173	$1,102.41	$1,102.40	$1,102.50