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	$176.76	10.698%	$195.6698	$195.67	$195.65	$195.70
Purchase #2	$10.46	3.474%	$10.8234	$10.82	$10.80	$10.80
Purchase #3	$42.83	5.772%	$45.3021	$45.30	$45.30	$45.30
Purchase #4	$99.26	10.111%	$109.2962	$109.30	$109.30	$109.30
Purchase #5	$17.66	11.135%	$19.6264	$19.63	$19.65	$19.60
Purchase #6	$43.82	12.840%	$49.4465	$49.45	$49.45	$49.40
Purchase #7	$69.37	13.207%	$78.5317	$78.53	$78.55	$78.50
7 purchase totals =	$460.16		$508.6961	$508.70	$508.70	$508.60