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	$90.86	3.648%	$94.1746	$94.17	$94.15	$94.20
Purchase #2	$202.83	5.629%	$214.2473	$214.25	$214.25	$214.20
Purchase #3	$173.64	12.256%	$194.9213	$194.92	$194.90	$194.90
Purchase #4	$152.54	7.823%	$164.4732	$164.47	$164.45	$164.50
Purchase #5	$55.29	13.482%	$62.7442	$62.74	$62.75	$62.70
Purchase #6	$249.59	9.190%	$272.5273	$272.53	$272.55	$272.50
Purchase #7	$39.74	7.303%	$42.6422	$42.64	$42.65	$42.60
7 purchase totals =	$964.49		$1,045.7301	$1,045.72	$1,045.70	$1,045.60