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	$177.81	8.352%	$192.6607	$192.66	$192.65	$192.70
Purchase #2	$193.36	11.330%	$215.2677	$215.27	$215.25	$215.30
Purchase #3	$173.98	10.331%	$191.9539	$191.95	$191.95	$192.00
Purchase #4	$96.55	3.134%	$99.5759	$99.58	$99.60	$99.60
Purchase #5	$85.59	4.669%	$89.5862	$89.59	$89.60	$89.60
Purchase #6	$192.71	13.344%	$218.4252	$218.43	$218.45	$218.40
Purchase #7	$26.68	12.242%	$29.9462	$29.95	$29.95	$29.90
7 purchase totals =	$946.68		$1,037.4158	$1,037.43	$1,037.45	$1,037.50