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	$35.36	4.535%	$36.9636	$36.96	$36.95	$37.00
Purchase #2	$91.30	10.151%	$100.5679	$100.57	$100.55	$100.60
Purchase #3	$144.52	4.599%	$151.1665	$151.17	$151.15	$151.20
Purchase #4	$237.26	6.412%	$252.4731	$252.47	$252.45	$252.50
Purchase #5	$221.89	3.207%	$229.006	$229.01	$229.00	$229.00
Purchase #6	$92.57	13.574%	$105.1355	$105.14	$105.15	$105.10
Purchase #7	$195.96	6.192%	$208.0938	$208.09	$208.10	$208.10
7 purchase totals =	$1,018.86		$1,083.4064	$1,083.41	$1,083.35	$1,083.50