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	$106.95	4.482%	$111.7435	$111.74	$111.75	$111.70
Purchase #2	$35.86	4.783%	$37.5752	$37.58	$37.60	$37.60
Purchase #3	$94.39	5.478%	$99.5607	$99.56	$99.55	$99.60
Purchase #4	$247.60	4.729%	$259.309	$259.31	$259.30	$259.30
Purchase #5	$125.42	13.682%	$142.58	$142.58	$142.60	$142.60
Purchase #6	$55.75	10.121%	$61.3925	$61.39	$61.40	$61.40
Purchase #7	$98.42	9.152%	$107.4274	$107.43	$107.45	$107.40
7 purchase totals =	$764.39		$819.5883	$819.59	$819.65	$819.60