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	$152.52	13.233%	$172.703	$172.70	$172.70	$172.70
Purchase #2	$206.99	4.691%	$216.6999	$216.70	$216.70	$216.70
Purchase #3	$150.33	3.306%	$155.2999	$155.30	$155.30	$155.30
Purchase #4	$40.71	12.112%	$45.6408	$45.64	$45.65	$45.60
Purchase #5	$228.61	8.762%	$248.6408	$248.64	$248.65	$248.60
Purchase #6	$36.40	11.577%	$40.614	$40.61	$40.60	$40.60
Purchase #7	$161.95	12.172%	$181.6626	$181.66	$181.65	$181.70
7 purchase totals =	$977.51		$1,061.2610	$1,061.25	$1,061.25	$1,061.20