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	$82.60	12.281%	$92.7441	$92.74	$92.75	$92.70
Purchase #2	$165.90	4.823%	$173.9014	$173.90	$173.90	$173.90
Purchase #3	$69.26	4.297%	$72.2361	$72.24	$72.25	$72.20
Purchase #4	$129.59	9.728%	$142.1965	$142.20	$142.20	$142.20
Purchase #5	$225.93	9.369%	$247.0974	$247.10	$247.10	$247.10
Purchase #6	$78.61	4.662%	$82.2748	$82.27	$82.25	$82.30
Purchase #7	$244.53	4.761%	$256.1721	$256.17	$256.15	$256.20
7 purchase totals =	$996.42		$1,066.6224	$1,066.62	$1,066.60	$1,066.60