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	$161.58	7.127%	$173.0958	$173.10	$173.10	$173.10
Purchase #2	$151.89	6.402%	$161.614	$161.61	$161.60	$161.60
Purchase #3	$182.29	7.726%	$196.3737	$196.37	$196.35	$196.40
Purchase #4	$128.30	12.358%	$144.1553	$144.16	$144.15	$144.20
Purchase #5	$157.70	10.535%	$174.3137	$174.31	$174.30	$174.30
Purchase #6	$152.35	10.689%	$168.6347	$168.63	$168.65	$168.60
Purchase #7	$130.56	9.838%	$143.4045	$143.40	$143.40	$143.40
7 purchase totals =	$1,064.67		$1,161.5917	$1,161.58	$1,161.55	$1,161.60