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	$226.77	7.461%	$243.6893	$243.69	$243.70	$243.70
Purchase #2	$94.32	6.522%	$100.4716	$100.47	$100.45	$100.50
Purchase #3	$162.33	9.438%	$177.6507	$177.65	$177.65	$177.70
Purchase #4	$95.77	4.545%	$100.1227	$100.12	$100.10	$100.10
Purchase #5	$135.78	8.159%	$146.8583	$146.86	$146.85	$146.90
Purchase #6	$186.78	3.272%	$192.8914	$192.89	$192.90	$192.90
Purchase #7	$53.70	10.187%	$59.1704	$59.17	$59.15	$59.20
7 purchase totals =	$955.45		$1,020.8544	$1,020.85	$1,020.80	$1,021.00