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	$48.25	10.722%	$53.4234	$53.42	$53.40	$53.40
Purchase #2	$43.78	4.497%	$45.7488	$45.75	$45.75	$45.70
Purchase #3	$100.73	5.137%	$105.9045	$105.90	$105.90	$105.90
Purchase #4	$226.64	7.295%	$243.1734	$243.17	$243.15	$243.20
Purchase #5	$169.45	8.303%	$183.5194	$183.52	$183.50	$183.50
Purchase #6	$242.51	12.797%	$273.544	$273.54	$273.55	$273.50
Purchase #7	$243.48	7.617%	$262.0259	$262.03	$262.05	$262.00
7 purchase totals =	$1,074.84		$1,167.3394	$1,167.33	$1,167.30	$1,167.20