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	$72.54	13.530%	$82.3547	$82.35	$82.35	$82.40
Purchase #2	$146.51	10.570%	$161.9961	$162.00	$162.00	$162.00
Purchase #3	$51.59	8.329%	$55.8869	$55.89	$55.90	$55.90
Purchase #4	$221.78	13.349%	$251.3854	$251.39	$251.40	$251.40
Purchase #5	$196.41	4.455%	$205.1601	$205.16	$205.15	$205.20
Purchase #6	$165.52	4.180%	$172.4387	$172.44	$172.45	$172.40
Purchase #7	$89.47	5.745%	$94.6101	$94.61	$94.60	$94.60
7 purchase totals =	$943.82		$1,023.8320	$1,023.84	$1,023.85	$1,023.90