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	$173.72	11.641%	$193.9427	$193.94	$193.95	$193.90
Purchase #2	$184.86	11.523%	$206.1614	$206.16	$206.15	$206.20
Purchase #3	$59.90	4.401%	$62.5362	$62.54	$62.55	$62.50
Purchase #4	$61.83	13.448%	$70.1449	$70.14	$70.15	$70.10
Purchase #5	$70.57	3.277%	$72.8826	$72.88	$72.90	$72.90
Purchase #6	$246.30	13.185%	$278.7747	$278.77	$278.75	$278.80
Purchase #7	$89.45	3.459%	$92.5441	$92.54	$92.55	$92.50
7 purchase totals =	$886.63		$976.9866	$976.97	$977.00	$976.90