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	$146.25	4.584%	$152.9541	$152.95	$152.95	$153.00
Purchase #2	$148.59	6.479%	$158.2171	$158.22	$158.20	$158.20
Purchase #3	$98.82	4.872%	$103.6345	$103.63	$103.65	$103.60
Purchase #4	$195.85	13.477%	$222.2447	$222.24	$222.25	$222.20
Purchase #5	$36.94	6.103%	$39.1944	$39.19	$39.20	$39.20
Purchase #6	$142.53	9.668%	$156.3098	$156.31	$156.30	$156.30
Purchase #7	$220.60	13.687%	$250.7935	$250.79	$250.80	$250.80
7 purchase totals =	$989.58		$1,083.3481	$1,083.33	$1,083.35	$1,083.30