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	$146.47	11.245%	$162.9406	$162.94	$162.95	$162.90
Purchase #2	$216.40	6.341%	$230.1219	$230.12	$230.10	$230.10
Purchase #3	$42.29	11.740%	$47.2548	$47.25	$47.25	$47.30
Purchase #4	$108.67	3.820%	$112.8212	$112.82	$112.80	$112.80
Purchase #5	$207.35	3.441%	$214.4849	$214.48	$214.50	$214.50
Purchase #6	$7.45	9.585%	$8.1641	$8.16	$8.15	$8.20
Purchase #7	$227.51	7.110%	$243.686	$243.69	$243.70	$243.70
7 purchase totals =	$956.14		$1,019.4735	$1,019.46	$1,019.45	$1,019.50