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	$12.59	13.149%	$14.2455	$14.25	$14.25	$14.20
Purchase #2	$107.48	3.566%	$111.3127	$111.31	$111.30	$111.30
Purchase #3	$103.29	7.809%	$111.3559	$111.36	$111.35	$111.40
Purchase #4	$130.97	11.867%	$146.5122	$146.51	$146.50	$146.50
Purchase #5	$30.72	4.763%	$32.1832	$32.18	$32.20	$32.20
Purchase #6	$191.43	11.607%	$213.6493	$213.65	$213.65	$213.60
Purchase #7	$94.98	7.315%	$101.9278	$101.93	$101.95	$101.90
7 purchase totals =	$671.46		$731.1866	$731.19	$731.20	$731.10