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	$88.66	8.155%	$95.8902	$95.89	$95.90	$95.90
Purchase #2	$64.43	11.272%	$71.6925	$71.69	$71.70	$71.70
Purchase #3	$202.75	13.841%	$230.8126	$230.81	$230.80	$230.80
Purchase #4	$217.42	12.337%	$244.2431	$244.24	$244.25	$244.20
Purchase #5	$73.52	10.695%	$81.383	$81.38	$81.40	$81.40
Purchase #6	$30.61	10.405%	$33.795	$33.80	$33.80	$33.80
Purchase #7	$196.43	10.726%	$217.4991	$217.50	$217.50	$217.50
7 purchase totals =	$873.82		$975.3155	$975.31	$975.35	$975.30