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	$169.28	10.827%	$187.6079	$187.61	$187.60	$187.60
Purchase #2	$36.78	11.670%	$41.0722	$41.07	$41.05	$41.10
Purchase #3	$76.71	11.404%	$85.458	$85.46	$85.45	$85.50
Purchase #4	$147.60	4.481%	$154.214	$154.21	$154.20	$154.20
Purchase #5	$158.87	4.317%	$165.7284	$165.73	$165.75	$165.70
Purchase #6	$183.70	10.703%	$203.3614	$203.36	$203.35	$203.40
Purchase #7	$250.56	5.412%	$264.1203	$264.12	$264.10	$264.10
7 purchase totals =	$1,023.50		$1,101.5622	$1,101.56	$1,101.50	$1,101.60