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	$168.29	4.209%	$175.3733	$175.37	$175.35	$175.40
Purchase #2	$53.59	10.409%	$59.1682	$59.17	$59.15	$59.20
Purchase #3	$147.32	10.802%	$163.2335	$163.23	$163.25	$163.20
Purchase #4	$64.87	3.370%	$67.0561	$67.06	$67.05	$67.10
Purchase #5	$181.75	8.241%	$196.728	$196.73	$196.75	$196.70
Purchase #6	$65.38	10.431%	$72.1998	$72.20	$72.20	$72.20
Purchase #7	$222.92	4.705%	$233.4084	$233.41	$233.40	$233.40
7 purchase totals =	$904.12		$967.1673	$967.17	$967.15	$967.20