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	$186.96	7.385%	$200.767	$200.77	$200.75	$200.80
Purchase #2	$187.61	13.472%	$212.8848	$212.88	$212.90	$212.90
Purchase #3	$43.86	11.631%	$48.9614	$48.96	$48.95	$49.00
Purchase #4	$10.60	5.470%	$11.1798	$11.18	$11.20	$11.20
Purchase #5	$209.68	7.358%	$225.1083	$225.11	$225.10	$225.10
Purchase #6	$199.70	12.629%	$224.9201	$224.92	$224.90	$224.90
Purchase #7	$144.28	12.515%	$162.3366	$162.34	$162.35	$162.30
7 purchase totals =	$982.69		$1,086.1580	$1,086.16	$1,086.15	$1,086.20