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	$148.47	9.217%	$162.1545	$162.15	$162.15	$162.20
Purchase #2	$61.26	5.355%	$64.5405	$64.54	$64.55	$64.50
Purchase #3	$47.28	13.547%	$53.685	$53.69	$53.70	$53.70
Purchase #4	$118.27	4.318%	$123.3769	$123.38	$123.40	$123.40
Purchase #5	$56.78	4.403%	$59.28	$59.28	$59.30	$59.30
Purchase #6	$7.96	4.248%	$8.2981	$8.30	$8.30	$8.30
Purchase #7	$159.26	9.296%	$174.0648	$174.06	$174.05	$174.10
7 purchase totals =	$599.28		$645.3998	$645.40	$645.45	$645.50