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	$165.78	4.874%	$173.8601	$173.86	$173.85	$173.90
Purchase #2	$79.47	9.868%	$87.3121	$87.31	$87.30	$87.30
Purchase #3	$57.48	3.316%	$59.386	$59.39	$59.40	$59.40
Purchase #4	$160.35	5.556%	$169.259	$169.26	$169.25	$169.30
Purchase #5	$250.83	11.120%	$278.7223	$278.72	$278.70	$278.70
Purchase #6	$184.76	13.501%	$209.7044	$209.70	$209.70	$209.70
Purchase #7	$153.31	9.408%	$167.7334	$167.73	$167.75	$167.70
7 purchase totals =	$1,051.98		$1,145.9773	$1,145.97	$1,145.95	$1,146.00