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	$59.28	9.372%	$64.8357	$64.84	$64.85	$64.80
Purchase #2	$209.58	10.346%	$231.2631	$231.26	$231.25	$231.30
Purchase #3	$192.73	4.236%	$200.894	$200.89	$200.90	$200.90
Purchase #4	$98.52	3.459%	$101.9278	$101.93	$101.95	$101.90
Purchase #5	$105.81	4.511%	$110.5831	$110.58	$110.60	$110.60
Purchase #6	$139.42	4.213%	$145.2938	$145.29	$145.30	$145.30
Purchase #7	$241.64	4.811%	$253.2653	$253.27	$253.25	$253.30
7 purchase totals =	$1,046.98		$1,108.0628	$1,108.06	$1,108.10	$1,108.10