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	$172.63	13.709%	$196.2958	$196.30	$196.30	$196.30
Purchase #2	$65.55	10.392%	$72.362	$72.36	$72.35	$72.40
Purchase #3	$94.37	11.683%	$105.3952	$105.40	$105.40	$105.40
Purchase #4	$24.97	4.633%	$26.1269	$26.13	$26.15	$26.10
Purchase #5	$152.83	13.730%	$173.8136	$173.81	$173.80	$173.80
Purchase #6	$149.41	12.860%	$168.6241	$168.62	$168.60	$168.60
Purchase #7	$238.45	9.327%	$260.6902	$260.69	$260.70	$260.70
7 purchase totals =	$898.21		$1,003.3078	$1,003.31	$1,003.30	$1,003.30