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	$105.65	5.529%	$111.4914	$111.49	$111.50	$111.50
Purchase #2	$196.38	9.544%	$215.1225	$215.12	$215.10	$215.10
Purchase #3	$170.39	3.442%	$176.2548	$176.25	$176.25	$176.30
Purchase #4	$113.45	12.502%	$127.6335	$127.63	$127.65	$127.60
Purchase #5	$229.54	6.708%	$244.9375	$244.94	$244.95	$244.90
Purchase #6	$209.69	4.151%	$218.3942	$218.39	$218.40	$218.40
Purchase #7	$82.33	6.548%	$87.721	$87.72	$87.70	$87.70
7 purchase totals =	$1,107.43		$1,181.5549	$1,181.54	$1,181.55	$1,181.50