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	$147.36	10.453%	$162.7635	$162.76	$162.75	$162.80
Purchase #2	$214.87	6.221%	$228.2371	$228.24	$228.25	$228.20
Purchase #3	$235.63	12.592%	$265.3005	$265.30	$265.30	$265.30
Purchase #4	$58.46	12.273%	$65.6348	$65.63	$65.65	$65.60
Purchase #5	$158.83	3.532%	$164.4399	$164.44	$164.45	$164.40
Purchase #6	$119.95	6.131%	$127.3041	$127.30	$127.30	$127.30
Purchase #7	$161.50	4.526%	$168.8095	$168.81	$168.80	$168.80
7 purchase totals =	$1,096.60		$1,182.4894	$1,182.48	$1,182.50	$1,182.40