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	$119.85	6.584%	$127.7409	$127.74	$127.75	$127.70
Purchase #2	$240.88	4.161%	$250.903	$250.90	$250.90	$250.90
Purchase #3	$104.86	6.607%	$111.7881	$111.79	$111.80	$111.80
Purchase #4	$135.26	6.603%	$144.1912	$144.19	$144.20	$144.20
Purchase #5	$114.43	4.565%	$119.6537	$119.65	$119.65	$119.70
Purchase #6	$99.74	5.519%	$105.2447	$105.24	$105.25	$105.20
Purchase #7	$147.67	4.432%	$154.2147	$154.21	$154.20	$154.20
7 purchase totals =	$962.69		$1,013.7363	$1,013.72	$1,013.75	$1,013.70