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	$142.29	4.469%	$148.6489	$148.65	$148.65	$148.60
Purchase #2	$139.60	8.525%	$151.5009	$151.50	$151.50	$151.50
Purchase #3	$172.91	4.533%	$180.748	$180.75	$180.75	$180.70
Purchase #4	$105.87	3.326%	$109.3912	$109.39	$109.40	$109.40
Purchase #5	$250.82	5.329%	$264.1862	$264.19	$264.20	$264.20
Purchase #6	$40.77	11.821%	$45.5894	$45.59	$45.60	$45.60
Purchase #7	$128.85	6.815%	$137.6311	$137.63	$137.65	$137.60
7 purchase totals =	$981.11		$1,037.6957	$1,037.70	$1,037.75	$1,037.60