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	$146.50	11.200%	$162.908	$162.91	$162.90	$162.90
Purchase #2	$165.47	8.749%	$179.947	$179.95	$179.95	$179.90
Purchase #3	$243.59	4.209%	$253.8427	$253.84	$253.85	$253.80
Purchase #4	$29.75	9.827%	$32.6735	$32.67	$32.65	$32.70
Purchase #5	$152.96	12.633%	$172.2834	$172.28	$172.30	$172.30
Purchase #6	$140.42	3.500%	$145.3347	$145.33	$145.35	$145.30
Purchase #7	$94.47	10.147%	$104.0559	$104.06	$104.05	$104.10
7 purchase totals =	$973.16		$1,051.0452	$1,051.04	$1,051.05	$1,051.00