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	$241.72	9.355%	$264.3329	$264.33	$264.35	$264.30
Purchase #2	$182.26	7.139%	$195.2715	$195.27	$195.25	$195.30
Purchase #3	$190.73	5.180%	$200.6098	$200.61	$200.60	$200.60
Purchase #4	$19.28	13.126%	$21.8107	$21.81	$21.80	$21.80
Purchase #5	$215.67	4.435%	$225.235	$225.24	$225.25	$225.20
Purchase #6	$168.59	9.275%	$184.2267	$184.23	$184.25	$184.20
Purchase #7	$90.56	3.612%	$93.831	$93.83	$93.85	$93.80
7 purchase totals =	$1,108.81		$1,185.3176	$1,185.32	$1,185.35	$1,185.20