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	$101.87	10.192%	$112.2526	$112.25	$112.25	$112.30
Purchase #2	$34.32	4.507%	$35.8668	$35.87	$35.85	$35.90
Purchase #3	$143.31	9.362%	$156.7267	$156.73	$156.75	$156.70
Purchase #4	$134.50	11.837%	$150.4208	$150.42	$150.40	$150.40
Purchase #5	$174.64	9.762%	$191.6884	$191.69	$191.70	$191.70
Purchase #6	$152.73	6.454%	$162.5872	$162.59	$162.60	$162.60
Purchase #7	$244.67	5.492%	$258.1073	$258.11	$258.10	$258.10
7 purchase totals =	$986.04		$1,067.6498	$1,067.66	$1,067.65	$1,067.70