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	$207.57	7.711%	$223.5757	$223.58	$223.60	$223.60
Purchase #2	$58.48	3.159%	$60.3274	$60.33	$60.35	$60.30
Purchase #3	$159.60	3.657%	$165.4366	$165.44	$165.45	$165.40
Purchase #4	$56.69	7.361%	$60.863	$60.86	$60.85	$60.90
Purchase #5	$92.51	7.550%	$99.4945	$99.49	$99.50	$99.50
Purchase #6	$76.33	7.148%	$81.7861	$81.79	$81.80	$81.80
Purchase #7	$114.98	13.825%	$130.876	$130.88	$130.90	$130.90
7 purchase totals =	$766.16		$822.3593	$822.37	$822.45	$822.40