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	$56.99	5.866%	$60.333	$60.33	$60.35	$60.30
Purchase #2	$13.69	5.289%	$14.4141	$14.41	$14.40	$14.40
Purchase #3	$93.87	13.432%	$106.4786	$106.48	$106.50	$106.50
Purchase #4	$55.35	7.478%	$59.4891	$59.49	$59.50	$59.50
Purchase #5	$52.71	9.189%	$57.5535	$57.55	$57.55	$57.60
Purchase #6	$64.26	4.113%	$66.903	$66.90	$66.90	$66.90
Purchase #7	$92.74	11.192%	$103.1195	$103.12	$103.10	$103.10
7 purchase totals =	$429.61		$468.2908	$468.28	$468.30	$468.30