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	$215.25	9.782%	$236.3058	$236.31	$236.30	$236.30
Purchase #2	$48.59	4.402%	$50.7289	$50.73	$50.75	$50.70
Purchase #3	$220.48	11.830%	$246.5628	$246.56	$246.55	$246.60
Purchase #4	$112.71	5.173%	$118.5405	$118.54	$118.55	$118.50
Purchase #5	$35.64	3.103%	$36.7459	$36.75	$36.75	$36.70
Purchase #6	$238.74	6.711%	$254.7618	$254.76	$254.75	$254.80
Purchase #7	$105.41	6.188%	$111.9328	$111.93	$111.95	$111.90
7 purchase totals =	$976.82		$1,055.5785	$1,055.58	$1,055.60	$1,055.50