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	$204.37	9.486%	$223.7565	$223.76	$223.75	$223.80
Purchase #2	$47.79	5.647%	$50.4887	$50.49	$50.50	$50.50
Purchase #3	$32.95	13.487%	$37.394	$37.39	$37.40	$37.40
Purchase #4	$145.32	11.603%	$162.1815	$162.18	$162.20	$162.20
Purchase #5	$148.71	5.335%	$156.6437	$156.64	$156.65	$156.60
Purchase #6	$100.71	9.156%	$109.931	$109.93	$109.95	$109.90
Purchase #7	$23.59	4.805%	$24.7235	$24.72	$24.70	$24.70
7 purchase totals =	$703.44		$765.1189	$765.11	$765.15	$765.10