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	$53.67	11.154%	$59.6564	$59.66	$59.65	$59.70
Purchase #2	$28.55	3.832%	$29.644	$29.64	$29.65	$29.60
Purchase #3	$68.39	12.820%	$77.1576	$77.16	$77.15	$77.20
Purchase #4	$124.46	6.660%	$132.749	$132.75	$132.75	$132.70
Purchase #5	$199.28	6.566%	$212.3647	$212.36	$212.35	$212.40
Purchase #6	$154.38	6.417%	$164.2866	$164.29	$164.30	$164.30
Purchase #7	$105.54	3.261%	$108.9817	$108.98	$109.00	$109.00
7 purchase totals =	$734.27		$784.8400	$784.84	$784.85	$784.90