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	$186.35	9.530%	$204.1092	$204.11	$204.10	$204.10
Purchase #2	$44.36	9.553%	$48.5977	$48.60	$48.60	$48.60
Purchase #3	$53.88	9.605%	$59.0552	$59.06	$59.05	$59.10
Purchase #4	$85.69	4.695%	$89.7131	$89.71	$89.70	$89.70
Purchase #5	$87.73	13.408%	$99.4928	$99.49	$99.50	$99.50
Purchase #6	$66.81	5.663%	$70.5935	$70.59	$70.60	$70.60
Purchase #7	$226.78	5.560%	$239.389	$239.39	$239.40	$239.40
7 purchase totals =	$751.60		$810.9505	$810.95	$810.95	$811.00