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	$62.83	7.335%	$67.4386	$67.44	$67.45	$67.40
Purchase #2	$137.33	7.478%	$147.5995	$147.60	$147.60	$147.60
Purchase #3	$184.45	6.482%	$196.406	$196.41	$196.40	$196.40
Purchase #4	$80.31	7.651%	$86.4545	$86.45	$86.45	$86.50
Purchase #5	$230.30	8.851%	$250.6839	$250.68	$250.70	$250.70
Purchase #6	$193.53	3.678%	$200.648	$200.65	$200.65	$200.60
Purchase #7	$5.91	11.612%	$6.5963	$6.60	$6.60	$6.60
7 purchase totals =	$894.66		$955.8268	$955.83	$955.85	$955.80