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	$169.91	5.721%	$179.6306	$179.63	$179.65	$179.60
Purchase #2	$26.84	6.398%	$28.5572	$28.56	$28.55	$28.60
Purchase #3	$42.91	5.755%	$45.3795	$45.38	$45.40	$45.40
Purchase #4	$39.61	3.826%	$41.1255	$41.13	$41.15	$41.10
Purchase #5	$143.91	11.340%	$160.2294	$160.23	$160.25	$160.20
Purchase #6	$219.78	11.196%	$244.3866	$244.39	$244.40	$244.40
Purchase #7	$166.98	5.262%	$175.7665	$175.77	$175.75	$175.80
7 purchase totals =	$809.94		$875.0753	$875.09	$875.15	$875.10