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	$205.51	5.466%	$216.7432	$216.74	$216.75	$216.70
Purchase #2	$64.40	5.839%	$68.1603	$68.16	$68.15	$68.20
Purchase #3	$59.59	3.259%	$61.532	$61.53	$61.55	$61.50
Purchase #4	$241.37	11.773%	$269.7865	$269.79	$269.80	$269.80
Purchase #5	$212.59	7.588%	$228.7213	$228.72	$228.70	$228.70
Purchase #6	$20.77	3.179%	$21.4303	$21.43	$21.45	$21.40
Purchase #7	$141.42	4.824%	$148.2421	$148.24	$148.25	$148.20
7 purchase totals =	$945.65		$1,014.6157	$1,014.61	$1,014.65	$1,014.50