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	$171.87	13.651%	$195.332	$195.33	$195.35	$195.30
Purchase #2	$33.88	4.742%	$35.4866	$35.49	$35.50	$35.50
Purchase #3	$75.38	3.800%	$78.2444	$78.24	$78.25	$78.20
Purchase #4	$14.51	5.532%	$15.3127	$15.31	$15.30	$15.30
Purchase #5	$62.53	4.279%	$65.2057	$65.21	$65.20	$65.20
Purchase #6	$95.25	4.592%	$99.6239	$99.62	$99.60	$99.60
Purchase #7	$38.78	13.763%	$44.1173	$44.12	$44.10	$44.10
7 purchase totals =	$492.20		$533.3226	$533.32	$533.30	$533.20