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	$196.41	11.269%	$218.5434	$218.54	$218.55	$218.50
Purchase #2	$138.27	4.608%	$144.6415	$144.64	$144.65	$144.60
Purchase #3	$68.46	3.673%	$70.9745	$70.97	$70.95	$71.00
Purchase #4	$13.42	5.170%	$14.1138	$14.11	$14.10	$14.10
Purchase #5	$117.38	11.656%	$131.0618	$131.06	$131.05	$131.10
Purchase #6	$88.33	12.667%	$99.5188	$99.52	$99.50	$99.50
Purchase #7	$49.41	11.767%	$55.2241	$55.22	$55.20	$55.20
7 purchase totals =	$671.68		$734.0779	$734.06	$734.00	$734.00