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	$141.95	7.583%	$152.7141	$152.71	$152.70	$152.70
Purchase #2	$169.52	7.862%	$182.8477	$182.85	$182.85	$182.80
Purchase #3	$100.98	12.613%	$113.7166	$113.72	$113.70	$113.70
Purchase #4	$238.48	11.306%	$265.4425	$265.44	$265.45	$265.40
Purchase #5	$181.90	11.385%	$202.6093	$202.61	$202.60	$202.60
Purchase #6	$101.81	10.285%	$112.2812	$112.28	$112.30	$112.30
Purchase #7	$59.90	11.771%	$66.9508	$66.95	$66.95	$67.00
7 purchase totals =	$994.54		$1,096.5622	$1,096.56	$1,096.55	$1,096.50