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	$188.27	7.371%	$202.1474	$202.15	$202.15	$202.10
Purchase #2	$168.89	10.804%	$187.1369	$187.14	$187.15	$187.10
Purchase #3	$168.56	12.586%	$189.775	$189.78	$189.80	$189.80
Purchase #4	$82.30	4.850%	$86.2916	$86.29	$86.30	$86.30
Purchase #5	$142.28	11.505%	$158.6493	$158.65	$158.65	$158.60
Purchase #6	$190.55	12.477%	$214.3249	$214.32	$214.30	$214.30
Purchase #7	$53.56	12.848%	$60.4414	$60.44	$60.45	$60.40
7 purchase totals =	$994.41		$1,098.7665	$1,098.77	$1,098.80	$1,098.60