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	$193.71	7.865%	$208.9453	$208.95	$208.95	$208.90
Purchase #2	$83.59	4.734%	$87.5472	$87.55	$87.55	$87.50
Purchase #3	$109.73	8.309%	$118.8475	$118.85	$118.85	$118.80
Purchase #4	$65.89	9.428%	$72.1021	$72.10	$72.10	$72.10
Purchase #5	$177.82	5.196%	$187.0595	$187.06	$187.05	$187.10
Purchase #6	$248.44	6.410%	$264.365	$264.37	$264.35	$264.40
Purchase #7	$48.67	9.789%	$53.4343	$53.43	$53.45	$53.40
7 purchase totals =	$927.85		$992.3009	$992.31	$992.30	$992.20