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	$166.53	9.443%	$182.2554	$182.26	$182.25	$182.30
Purchase #2	$99.58	11.773%	$111.3036	$111.30	$111.30	$111.30
Purchase #3	$46.79	3.253%	$48.3121	$48.31	$48.30	$48.30
Purchase #4	$200.58	13.814%	$228.2881	$228.29	$228.30	$228.30
Purchase #5	$150.65	12.387%	$169.311	$169.31	$169.30	$169.30
Purchase #6	$197.48	10.161%	$217.5459	$217.55	$217.55	$217.50
Purchase #7	$196.95	6.488%	$209.7281	$209.73	$209.75	$209.70
7 purchase totals =	$1,058.56		$1,166.7442	$1,166.75	$1,166.75	$1,166.70