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	$200.78	3.623%	$208.0543	$208.05	$208.05	$208.10
Purchase #2	$205.75	13.661%	$233.8575	$233.86	$233.85	$233.90
Purchase #3	$211.82	4.461%	$221.2693	$221.27	$221.25	$221.30
Purchase #4	$103.30	7.398%	$110.9421	$110.94	$110.95	$110.90
Purchase #5	$43.42	6.748%	$46.35	$46.35	$46.35	$46.40
Purchase #6	$28.65	13.602%	$32.547	$32.55	$32.55	$32.50
Purchase #7	$89.57	6.524%	$95.4135	$95.41	$95.40	$95.40
7 purchase totals =	$883.29		$948.4337	$948.43	$948.40	$948.50