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	$141.76	7.480%	$152.3636	$152.36	$152.35	$152.40
Purchase #2	$212.70	11.613%	$237.4009	$237.40	$237.40	$237.40
Purchase #3	$71.76	8.801%	$78.0756	$78.08	$78.10	$78.10
Purchase #4	$102.33	10.731%	$113.311	$113.31	$113.30	$113.30
Purchase #5	$180.96	3.431%	$187.1687	$187.17	$187.15	$187.20
Purchase #6	$29.54	13.546%	$33.5415	$33.54	$33.55	$33.50
Purchase #7	$54.98	10.865%	$60.9536	$60.95	$60.95	$61.00
7 purchase totals =	$794.03		$862.8149	$862.81	$862.80	$862.90