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	$148.84	5.406%	$156.8863	$156.89	$156.90	$156.90
Purchase #2	$112.40	3.349%	$116.1643	$116.16	$116.15	$116.20
Purchase #3	$161.27	6.483%	$171.7251	$171.73	$171.75	$171.70
Purchase #4	$158.46	8.685%	$172.2223	$172.22	$172.20	$172.20
Purchase #5	$187.45	5.417%	$197.6042	$197.60	$197.60	$197.60
Purchase #6	$110.70	7.125%	$118.5874	$118.59	$118.60	$118.60
Purchase #7	$194.47	13.713%	$221.1377	$221.14	$221.15	$221.10
7 purchase totals =	$1,073.59		$1,154.3273	$1,154.33	$1,154.35	$1,154.30