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	$172.35	13.763%	$196.0705	$196.07	$196.05	$196.10
Purchase #2	$188.41	11.867%	$210.7686	$210.77	$210.75	$210.80
Purchase #3	$67.70	7.177%	$72.5588	$72.56	$72.55	$72.60
Purchase #4	$122.27	6.448%	$130.154	$130.15	$130.15	$130.20
Purchase #5	$52.28	5.427%	$55.1172	$55.12	$55.10	$55.10
Purchase #6	$212.30	4.775%	$222.4373	$222.44	$222.45	$222.40
Purchase #7	$144.54	7.853%	$155.8907	$155.89	$155.90	$155.90
7 purchase totals =	$959.85		$1,042.9971	$1,043.00	$1,042.95	$1,043.10