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	$231.28	13.469%	$262.4311	$262.43	$262.45	$262.40
Purchase #2	$35.72	5.443%	$37.6642	$37.66	$37.65	$37.70
Purchase #3	$170.68	4.371%	$178.1404	$178.14	$178.15	$178.10
Purchase #4	$74.44	12.672%	$83.873	$83.87	$83.85	$83.90
Purchase #5	$223.83	3.324%	$231.2701	$231.27	$231.25	$231.30
Purchase #6	$148.82	4.226%	$155.1091	$155.11	$155.10	$155.10
Purchase #7	$218.74	11.324%	$243.5101	$243.51	$243.50	$243.50
7 purchase totals =	$1,103.51		$1,191.9980	$1,191.99	$1,191.95	$1,192.00