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	$175.56	11.858%	$196.3779	$196.38	$196.40	$196.40
Purchase #2	$85.85	3.459%	$88.8196	$88.82	$88.80	$88.80
Purchase #3	$116.88	8.746%	$127.1023	$127.10	$127.10	$127.10
Purchase #4	$180.86	12.282%	$203.0732	$203.07	$203.05	$203.10
Purchase #5	$109.68	5.534%	$115.7497	$115.75	$115.75	$115.70
Purchase #6	$22.34	9.125%	$24.3785	$24.38	$24.40	$24.40
Purchase #7	$178.72	10.148%	$196.8565	$196.86	$196.85	$196.90
7 purchase totals =	$869.89		$952.3577	$952.36	$952.35	$952.40