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	$169.60	7.488%	$182.2996	$182.30	$182.30	$182.30
Purchase #2	$123.35	7.501%	$132.6025	$132.60	$132.60	$132.60
Purchase #3	$196.29	3.506%	$203.1719	$203.17	$203.15	$203.20
Purchase #4	$195.89	3.754%	$203.2437	$203.24	$203.25	$203.20
Purchase #5	$160.79	9.705%	$176.3947	$176.39	$176.40	$176.40
Purchase #6	$81.85	10.848%	$90.7291	$90.73	$90.75	$90.70
Purchase #7	$116.72	9.546%	$127.8621	$127.86	$127.85	$127.90
7 purchase totals =	$1,044.49		$1,116.3036	$1,116.29	$1,116.30	$1,116.30