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	$189.53	3.728%	$196.5957	$196.60	$196.60	$196.60
Purchase #2	$161.47	11.171%	$179.5078	$179.51	$179.50	$179.50
Purchase #3	$66.47	7.337%	$71.3469	$71.35	$71.35	$71.30
Purchase #4	$92.28	10.244%	$101.7332	$101.73	$101.75	$101.70
Purchase #5	$21.46	4.794%	$22.4888	$22.49	$22.50	$22.50
Purchase #6	$242.81	13.352%	$275.23	$275.23	$275.25	$275.20
Purchase #7	$243.51	6.784%	$260.0297	$260.03	$260.05	$260.00
7 purchase totals =	$1,017.53		$1,106.9321	$1,106.94	$1,107.00	$1,106.80