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	$180.64	9.553%	$197.8965	$197.90	$197.90	$197.90
Purchase #2	$188.67	4.364%	$196.9036	$196.90	$196.90	$196.90
Purchase #3	$196.69	8.532%	$213.4716	$213.47	$213.45	$213.50
Purchase #4	$178.60	6.546%	$190.2912	$190.29	$190.30	$190.30
Purchase #5	$89.96	10.115%	$99.0595	$99.06	$99.05	$99.10
Purchase #6	$84.58	8.870%	$92.0822	$92.08	$92.10	$92.10
Purchase #7	$195.80	6.707%	$208.9323	$208.93	$208.95	$208.90
7 purchase totals =	$1,114.94		$1,198.6369	$1,198.63	$1,198.65	$1,198.70