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	$117.66	6.856%	$125.7268	$125.73	$125.75	$125.70
Purchase #2	$78.40	3.236%	$80.937	$80.94	$80.95	$80.90
Purchase #3	$56.46	9.690%	$61.931	$61.93	$61.95	$61.90
Purchase #4	$33.63	12.369%	$37.7897	$37.79	$37.80	$37.80
Purchase #5	$81.26	11.261%	$90.4107	$90.41	$90.40	$90.40
Purchase #6	$102.27	13.869%	$116.4538	$116.45	$116.45	$116.50
Purchase #7	$149.33	11.335%	$166.2566	$166.26	$166.25	$166.30
7 purchase totals =	$619.01		$679.5056	$679.51	$679.55	$679.50