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	$219.52	13.375%	$248.8808	$248.88	$248.90	$248.90
Purchase #2	$56.81	8.333%	$61.544	$61.54	$61.55	$61.50
Purchase #3	$146.59	8.157%	$158.5473	$158.55	$158.55	$158.50
Purchase #4	$61.28	9.459%	$67.0765	$67.08	$67.10	$67.10
Purchase #5	$170.33	11.666%	$190.2007	$190.20	$190.20	$190.20
Purchase #6	$201.29	10.330%	$222.0833	$222.08	$222.10	$222.10
Purchase #7	$207.83	5.662%	$219.5973	$219.60	$219.60	$219.60
7 purchase totals =	$1,063.65		$1,167.9299	$1,167.93	$1,168.00	$1,167.90