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	$184.56	3.362%	$190.7649	$190.76	$190.75	$190.80
Purchase #2	$37.36	9.371%	$40.861	$40.86	$40.85	$40.90
Purchase #3	$30.33	13.110%	$34.3063	$34.31	$34.30	$34.30
Purchase #4	$234.86	4.571%	$245.5955	$245.60	$245.60	$245.60
Purchase #5	$211.26	5.632%	$223.1582	$223.16	$223.15	$223.20
Purchase #6	$138.88	9.321%	$151.825	$151.83	$151.85	$151.80
Purchase #7	$224.79	13.846%	$255.9144	$255.91	$255.90	$255.90
7 purchase totals =	$1,062.04		$1,142.4253	$1,142.43	$1,142.40	$1,142.50