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	$45.66	4.435%	$47.685	$47.69	$47.70	$47.70
Purchase #2	$100.65	4.648%	$105.3282	$105.33	$105.35	$105.30
Purchase #3	$247.90	7.518%	$266.5371	$266.54	$266.55	$266.50
Purchase #4	$194.79	5.263%	$205.0418	$205.04	$205.05	$205.00
Purchase #5	$102.50	3.502%	$106.0896	$106.09	$106.10	$106.10
Purchase #6	$159.52	7.412%	$171.3436	$171.34	$171.35	$171.30
Purchase #7	$199.34	11.510%	$222.284	$222.28	$222.30	$222.30
7 purchase totals =	$1,050.36		$1,124.3093	$1,124.31	$1,124.40	$1,124.20