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	$202.76	7.642%	$218.2549	$218.25	$218.25	$218.30
Purchase #2	$54.48	8.351%	$59.0296	$59.03	$59.05	$59.00
Purchase #3	$13.70	6.346%	$14.5694	$14.57	$14.55	$14.60
Purchase #4	$243.34	5.388%	$256.4512	$256.45	$256.45	$256.50
Purchase #5	$80.79	9.251%	$88.2639	$88.26	$88.25	$88.30
Purchase #6	$35.64	13.670%	$40.512	$40.51	$40.50	$40.50
Purchase #7	$103.33	5.826%	$109.35	$109.35	$109.35	$109.40
7 purchase totals =	$734.04		$786.4310	$786.42	$786.40	$786.60