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	$149.58	8.670%	$162.5486	$162.55	$162.55	$162.50
Purchase #2	$178.95	5.361%	$188.5435	$188.54	$188.55	$188.50
Purchase #3	$33.55	7.698%	$36.1327	$36.13	$36.15	$36.10
Purchase #4	$172.90	8.806%	$188.1256	$188.13	$188.15	$188.10
Purchase #5	$229.91	3.249%	$237.3798	$237.38	$237.40	$237.40
Purchase #6	$143.76	4.709%	$150.5297	$150.53	$150.55	$150.50
Purchase #7	$53.93	9.500%	$59.0534	$59.05	$59.05	$59.10
7 purchase totals =	$962.58		$1,022.3133	$1,022.31	$1,022.40	$1,022.20