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	$191.47	10.720%	$211.9956	$212.00	$212.00	$212.00
Purchase #2	$80.54	10.688%	$89.1481	$89.15	$89.15	$89.10
Purchase #3	$145.62	3.698%	$151.005	$151.01	$151.00	$151.00
Purchase #4	$115.51	10.616%	$127.7725	$127.77	$127.75	$127.80
Purchase #5	$237.26	11.319%	$264.1155	$264.12	$264.10	$264.10
Purchase #6	$147.48	4.351%	$153.8969	$153.90	$153.90	$153.90
Purchase #7	$190.40	9.491%	$208.4709	$208.47	$208.45	$208.50
7 purchase totals =	$1,108.28		$1,206.4045	$1,206.42	$1,206.35	$1,206.40