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	$149.71	4.833%	$156.9455	$156.95	$156.95	$156.90
Purchase #2	$5.85	7.342%	$6.2795	$6.28	$6.30	$6.30
Purchase #3	$241.27	13.180%	$273.0694	$273.07	$273.05	$273.10
Purchase #4	$152.98	11.497%	$170.5681	$170.57	$170.55	$170.60
Purchase #5	$19.51	6.698%	$20.8168	$20.82	$20.80	$20.80
Purchase #6	$25.71	6.705%	$27.4339	$27.43	$27.45	$27.40
Purchase #7	$76.28	3.455%	$78.9155	$78.92	$78.90	$78.90
7 purchase totals =	$671.31		$734.0287	$734.04	$734.00	$734.00