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	$110.95	13.616%	$126.057	$126.06	$126.05	$126.10
Purchase #2	$29.67	10.602%	$32.8156	$32.82	$32.80	$32.80
Purchase #3	$33.37	11.583%	$37.2352	$37.24	$37.25	$37.20
Purchase #4	$95.73	10.114%	$105.4121	$105.41	$105.40	$105.40
Purchase #5	$217.62	10.311%	$240.0588	$240.06	$240.05	$240.10
Purchase #6	$77.37	11.321%	$86.1291	$86.13	$86.15	$86.10
Purchase #7	$71.44	8.714%	$77.6653	$77.67	$77.65	$77.70
7 purchase totals =	$636.15		$705.3731	$705.39	$705.35	$705.40